1
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Wu Y, Wang BY, Yu Y, Li Y, Ribeiro HB, Wang J, Xu R, Liu Y, Ye Y, Zhou J, Ke F, Harbola V, Heinz TF, Hwang HY, Cui Y. Interlayer engineering of Fe 3GeTe 2: From 3D superlattice to 2D monolayer. Proc Natl Acad Sci U S A 2024; 121:e2314454121. [PMID: 38232283 PMCID: PMC10823236 DOI: 10.1073/pnas.2314454121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 12/05/2023] [Indexed: 01/19/2024] Open
Abstract
The discoveries of ferromagnetism down to the atomically thin limit in van der Waals (vdW) crystals by mechanical exfoliation have enriched the family of magnetic thin films [C. Gong et al., Nature 546, 265-269 (2017) and B. Huang et al., Nature 546, 270-273 (2017)]. However, compared to the study of traditional magnetic thin films by physical deposition methods, the toolbox of the vdW crystals based on mechanical exfoliation and transfer suffers from low yield and ambient corrosion problem and now is facing new challenges to study magnetism. For example, the formation of magnetic superlattice is difficult in vdW crystals, which limits the study of the interlayer interaction in vdW crystals [M. Gibertini, M. Koperski, A. F. Morpurgo, K. S. Novoselov, Nat. Nanotechnol. 14, 408-419 (2019)]. Here, we report a strategy of interlayer engineering of the magnetic vdW crystal Fe3GeTe2 (FGT) by intercalating quaternary ammonium cations into the vdW spacing. Both three-dimensional (3D) vdW superlattice and two-dimensional (2D) vdW monolayer can be formed by using this method based on the amount of intercalant. On the one hand, the FGT superlattice shows a strong 3D critical behavior with a decreased coercivity and increased domain wall size, attributed to the co-engineering of the anisotropy, exchange interaction, and electron doping by intercalation. On the other hand, the 2D vdW few layers obtained by over-intercalation are capped with organic molecules from the bulk crystal, which not only enhances the ferromagnetic transition temperature (TC), but also substantially protects the thin samples from degradation, thus allowing the preparation of large-scale FGT ink in ambient environment.
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Affiliation(s)
- Yecun Wu
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA94025
- Department of Electrical Engineering, Stanford University, Stanford, CA94305
- Department of Physics, Stanford University, Stanford, CA94305
| | - Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA94025
- Department of Physics, Stanford University, Stanford, CA94305
| | - Yijun Yu
- Department of Applied Physics, Stanford University, Stanford, CA94305
| | - Yanbin Li
- Department of Materials Science and Engineering, Stanford University, Stanford, CA94305
| | - Henrique B. Ribeiro
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA94025
| | - Jierong Wang
- Department of Applied Physics, Stanford University, Stanford, CA94305
| | - Rong Xu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA94305
| | - Yunzhi Liu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA94305
| | - Yusheng Ye
- Department of Materials Science and Engineering, Stanford University, Stanford, CA94305
| | - Jiawei Zhou
- Department of Materials Science and Engineering, Stanford University, Stanford, CA94305
| | - Feng Ke
- Department of Geological Science, Stanford University, Stanford, CA94305
| | - Varun Harbola
- Department of Physics, Stanford University, Stanford, CA94305
| | - Tony F. Heinz
- Department of Applied Physics, Stanford University, Stanford, CA94305
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA94025
| | - Harold Y. Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA94025
- Department of Applied Physics, Stanford University, Stanford, CA94305
| | - Yi Cui
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA94025
- Department of Materials Science and Engineering, Stanford University, Stanford, CA94305
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2
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Cui Y, Wang J, Li Y, Wu Y, Been E, Zhang Z, Zhou J, Zhang W, Hwang HY, Sinclair R, Cui Y. Twisted epitaxy of gold nanodisks grown between twisted substrate layers of molybdenum disulfide. Science 2024; 383:212-219. [PMID: 38207038 DOI: 10.1126/science.adk5947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 11/27/2023] [Indexed: 01/13/2024]
Abstract
We expand the concept of epitaxy to a regime of "twisted epitaxy" with the epilayer crystal orientation between two substrates influenced by their relative orientation. We annealed nanometer-thick gold (Au) nanoparticles between two substrates of exfoliated hexagonal molybdenum disulfide (MoS2) with varying orientation of their basal planes with a mutual twist angle ranging from 0° to 60°. Transmission electron microscopy studies show that Au aligns midway between the top and bottom MoS2 when the twist angle of the bilayer is small (<~7°). For larger twist angles, Au has only a small misorientation with the bottom MoS2 that varies approximately sinusoidally with twist angle of the bilayer MoS2. Four-dimensional scanning transmission electron microscopy analysis further reveals a periodic strain variation (<|±0.5%|) in the Au nanodisks associated with the twisted epitaxy, consistent with the Moiré registry of the two MoS2 twisted layers.
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Affiliation(s)
- Yi Cui
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Jingyang Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94305, USA
| | - Yanbin Li
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Yecun Wu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Emily Been
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Zewen Zhang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Jiawei Zhou
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Wenbo Zhang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Harold Y Hwang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Robert Sinclair
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Yi Cui
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Energy Science and Engineering, Stanford University, Stanford, CA 94305, USA
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3
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Cheng B, Cheng D, Lee K, Luo L, Chen Z, Lee Y, Wang BY, Mootz M, Perakis IE, Shen ZX, Hwang HY, Wang J. Evidence for d-wave superconductivity of infinite-layer nickelates from low-energy electrodynamics. Nat Mater 2024:10.1038/s41563-023-01766-z. [PMID: 38182811 DOI: 10.1038/s41563-023-01766-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 11/17/2023] [Indexed: 01/07/2024]
Abstract
The discovery of superconductivity in infinite-layer nickelates established another category of unconventional superconductors that shares structural and electronic similarities with cuprates. However, key issues of the superconducting pairing symmetry, gap amplitude and superconducting fluctuations are yet to be addressed. Here we utilize static and ultrafast terahertz spectroscopy to address these. We demonstrate that the equilibrium terahertz conductivity and non-equilibrium terahertz responses of an optimally Sr-doped nickelate film (superconducting transition temperature of Tc = 17 K) are in line with the electrodynamics of d-wave superconductivity in the dirty limit. The gap-to-Tc ratio (2Δ/kBTc) is found to be 3.4, indicating that the superconductivity falls in the weak coupling regime. In addition, we observed substantial superconducting fluctuations near Tc that do not extend into the deep normal state as the optimally hole-doped cuprates do. Our results support a d-wave system that closely resembles the electron-doped cuprates.
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Affiliation(s)
- Bing Cheng
- Ames National Laboratory, Ames, IA, USA.
| | - Di Cheng
- Ames National Laboratory, Ames, IA, USA
| | - Kyuho Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Liang Luo
- Ames National Laboratory, Ames, IA, USA
| | - Zhuoyu Chen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
- Department of Physics, Southern University of Science and Technology, Shenzhen, China
| | - Yonghun Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Martin Mootz
- Ames National Laboratory, Ames, IA, USA
- Department of Physics and Astronomy, Iowa State University, Ames, IA, USA
| | - Ilias E Perakis
- Department of Physics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Zhi-Xun Shen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Jigang Wang
- Ames National Laboratory, Ames, IA, USA.
- Department of Physics and Astronomy, Iowa State University, Ames, IA, USA.
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4
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Su Y, Zong A, Kogar A, Lu D, Hong SS, Freelon B, Rohwer T, Wang BY, Hwang HY, Gedik N. Delamination-Assisted Ultrafast Wrinkle Formation in a Freestanding Film. Nano Lett 2023. [PMID: 37988604 DOI: 10.1021/acs.nanolett.3c02898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2023]
Abstract
Freestanding films provide a versatile platform for materials engineering thanks to additional structural motifs not found in films with a substrate. A ubiquitous example is wrinkles, yet little is known about how they can develop over as fast as a few picoseconds due to a lack of experimental probes to visualize their dynamics in real time on the nanoscopic scale. Here, we use time-resolved electron diffraction to directly observe light-activated wrinkling formation in freestanding La2/3Ca1/3MnO3 films. Via a "lock-in" analysis of oscillations in the diffraction peak position, intensity, and width, we quantitatively reconstructed how wrinkles develop on the time scale of lattice vibration. Contrary to the common assumption of fixed boundary conditions, we found that wrinkle development is associated with ultrafast delamination at the film boundaries. Our work provides a generic protocol to quantify wrinkling dynamics in freestanding films and highlights the importance of the film-substrate interaction in determining the properties of freestanding structures.
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Affiliation(s)
- Yifan Su
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
| | - Alfred Zong
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
- University of California at Berkeley, Department of Chemistry, Berkeley, California 94720, United States
| | - Anshul Kogar
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
| | - Di Lu
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Seung Sae Hong
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Byron Freelon
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
| | - Timm Rohwer
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
| | - Bai Yang Wang
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Harold Y Hwang
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Nuh Gedik
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
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5
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Hotz MT, Martis J, Radlicka T, Bacon NJ, Dellby N, Lovejoy TC, Quillin SC, Hwang HY, Singh P, Krivanek OL. Atomic Resolution SE Imaging in a 30-200 keV Aberration-corrected UHV STEM. Microsc Microanal 2023; 29:2064-2065. [PMID: 37612905 DOI: 10.1093/micmic/ozad067.1068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- M T Hotz
- Nion R&D, 11511 NE 118th St, Kirkland, WA, USA
| | - J Martis
- Nion R&D, 11511 NE 118th St, Kirkland, WA, USA
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - T Radlicka
- Institute of Scientific Instruments of CAS, Královopolská 147, Brno, Czech Republic
| | - N J Bacon
- Nion R&D, 11511 NE 118th St, Kirkland, WA, USA
| | - N Dellby
- Nion R&D, 11511 NE 118th St, Kirkland, WA, USA
| | - T C Lovejoy
- Nion R&D, 11511 NE 118th St, Kirkland, WA, USA
| | - S C Quillin
- Nion R&D, 11511 NE 118th St, Kirkland, WA, USA
| | - H Y Hwang
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - P Singh
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - O L Krivanek
- Nion R&D, 11511 NE 118th St, Kirkland, WA, USA
- Department of Physics, Arizona State University, Tempe, AZ, USA
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6
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Harikrishnan KP, Li YE, Crust KJ, Khandelwal A, Shao YT, Chen Z, Zhang C, Guguschev C, Xu R, Hwang HY, Schlom DG, Muller DA. Visualizing Polar Distortions and Interface Effects with Multislice Ptychography. Microsc Microanal 2023; 29:1626-1627. [PMID: 37613802 DOI: 10.1093/micmic/ozad067.835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- K P Harikrishnan
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
| | | | - Kevin J Crust
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, United States
- Department of Physics, Stanford University, Stanford, CA, United States
| | - Aarushi Khandelwal
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, United States
- Department of Applied Physics, Stanford University, Stanford, CA, United States
| | - Yu-Tsun Shao
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, United States
| | - Zhen Chen
- School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Chenyu Zhang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
| | | | - Ruijuan Xu
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, United States
- Department of Applied Physics, Stanford University, Stanford, CA, United States
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, United States
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, United States
- Department of Applied Physics, Stanford University, Stanford, CA, United States
| | - Darrell G Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, United States
- Leibniz-Institut für Kristallzüchtung, Berlin, Germany
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, United States
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, United States
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7
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Kim WJ, Smeaton MA, Jia C, Goodge BH, Cho BG, Lee K, Osada M, Jost D, Ievlev AV, Moritz B, Kourkoutis LF, Devereaux TP, Hwang HY. Publisher Correction: Geometric frustration of Jahn-Teller order in the infinite-layer lattice. Nature 2023:10.1038/s41586-023-06432-7. [PMID: 37474799 DOI: 10.1038/s41586-023-06432-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/22/2023]
Affiliation(s)
- Woo Jin Kim
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
- Department of Applied Physics, Stanford University, Stanford, CA, USA.
| | - Michelle A Smeaton
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA
| | - Chunjing Jia
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, University of Florida, Gainesville, FL, USA
| | - Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Byeong-Gwan Cho
- Pohang Accelerator Laboratory, POSTECH, Pohang, Republic of Korea
| | - Kyuho Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Motoki Osada
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Daniel Jost
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Anton V Ievlev
- Center for Nanophase Materials Sciences Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Brian Moritz
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Thomas P Devereaux
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
- Department of Applied Physics, Stanford University, Stanford, CA, USA.
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8
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Lee K, Wang BY, Osada M, Goodge BH, Wang TC, Lee Y, Harvey S, Kim WJ, Yu Y, Murthy C, Raghu S, Kourkoutis LF, Hwang HY. Linear-in-temperature resistivity for optimally superconducting (Nd,Sr)NiO 2. Nature 2023; 619:288-292. [PMID: 37438595 DOI: 10.1038/s41586-023-06129-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/25/2023] [Indexed: 07/14/2023]
Abstract
The occurrence of superconductivity in proximity to various strongly correlated phases of matter has drawn extensive focus on their normal state properties, to develop an understanding of the state from which superconductivity emerges1-4. The recent finding of superconductivity in layered nickelates raises similar interests5-8. However, transport measurements of doped infinite-layer nickelate thin films have been hampered by materials limitations of these metastable compounds: in particular, a high density of extended defects9-11. Here, by moving to a substrate (LaAlO3)0.3(Sr2TaAlO6)0.7 that better stabilizes the growth and reduction conditions, we can synthesize the doping series of Nd1-xSrxNiO2 essentially free from extended defects. In their absence, the normal state resistivity shows a low-temperature upturn in the underdoped regime, linear behaviour near optimal doping and quadratic temperature dependence for overdoping. This is phenomenologically similar to the copper oxides2,12 despite key distinctions-namely, the absence of an insulating parent compound5,6,9,10, multiband electronic structure13,14 and a Mott-Hubbard orbital alignment rather than the charge-transfer insulator of the copper oxides15,16. We further observe an enhancement of superconductivity, both in terms of transition temperature and range of doping. These results indicate a convergence in the electronic properties of both superconducting families as the scale of disorder in the nickelates is reduced.
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Affiliation(s)
- Kyuho Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
- Department of Physics, Stanford University, Stanford, CA, USA.
| | - Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Motoki Osada
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Tiffany C Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Yonghun Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Shannon Harvey
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Woo Jin Kim
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Yijun Yu
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | | | - Srinivas Raghu
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
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9
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Wang BY, Wang TC, Hsu YT, Osada M, Lee K, Jia C, Duffy C, Li D, Fowlie J, Beasley MR, Devereaux TP, Fisher IR, Hussey NE, Hwang HY. Effects of rare-earth magnetism on the superconducting upper critical field in infinite-layer nickelates. Sci Adv 2023; 9:eadf6655. [PMID: 37196089 DOI: 10.1126/sciadv.adf6655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 04/14/2023] [Indexed: 05/19/2023]
Abstract
The search for superconductivity in infinite-layer nickelates was motivated by analogy to the cuprates, and this perspective has framed much of the initial consideration of this material. However, a growing number of studies have highlighted the involvement of rare-earth orbitals; in that context, the consequences of varying the rare-earth element in the superconducting nickelates have been much debated. Here, we show notable differences in the magnitude and anisotropy of the superconducting upper critical field across the La-, Pr-, and Nd-nickelates. These distinctions originate from the 4f electron characteristics of the rare-earth ions in the lattice: They are absent for La3+, nonmagnetic for the Pr3+ singlet ground state, and magnetic for the Nd3+ Kramer's doublet. The unique polar and azimuthal angle-dependent magnetoresistance found in the Nd-nickelates can be understood to arise from the magnetic contribution of the Nd3+ 4f moments. Such robust and tunable superconductivity suggests potential in future high-field applications.
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Affiliation(s)
- Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Tiffany C Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Yu-Te Hsu
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, Netherlands
| | - Motoki Osada
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Kyuho Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Chunjing Jia
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Caitlin Duffy
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, Netherlands
| | - Danfeng Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Jennifer Fowlie
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Malcolm R Beasley
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Thomas P Devereaux
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Ian R Fisher
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Nigel E Hussey
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, Netherlands
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
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10
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Goodge BH, Geisler B, Lee K, Osada M, Wang BY, Li D, Hwang HY, Pentcheva R, Kourkoutis LF. Resolving the polar interface of infinite-layer nickelate thin films. Nat Mater 2023; 22:466-473. [PMID: 36973543 DOI: 10.1038/s41563-023-01510-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/14/2023] [Indexed: 06/18/2023]
Abstract
Nickel-based superconductors provide a long-awaited experimental platform to explore possible cuprate-like superconductivity. Despite similar crystal structure and d electron filling, however, superconductivity in nickelates has thus far only been stabilized in thin-film geometry, raising questions about the polar interface between substrate and thin film. Here we conduct a detailed experimental and theoretical study of the prototypical interface between Nd1-xSrxNiO2 and SrTiO3. Atomic-resolution electron energy loss spectroscopy in the scanning transmission electron microscope reveals the formation of a single intermediate Nd(Ti,Ni)O3 layer. Density functional theory calculations with a Hubbard U term show how the observed structure alleviates the polar discontinuity. We explore the effects of oxygen occupancy, hole doping and cation structure to disentangle the contributions of each for reducing interface charge density. Resolving the non-trivial interface structure will be instructive for future synthesis of nickelate films on other substrates and in vertical heterostructures.
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Affiliation(s)
- Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA.
| | - Benjamin Geisler
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Duisburg, Germany
| | - Kyuho Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Motoki Osada
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Danfeng Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, USA
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Rossitza Pentcheva
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Duisburg, Germany
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA.
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11
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Xu R, Crust KJ, Harbola V, Arras R, Patel KY, Prosandeev S, Cao H, Shao YT, Behera P, Caretta L, Kim WJ, Khandelwal A, Acharya M, Wang MM, Liu Y, Barnard ES, Raja A, Martin LW, Gu XW, Zhou H, Ramesh R, Muller DA, Bellaiche L, Hwang HY. Size-Induced Ferroelectricity in Antiferroelectric Oxide Membranes. Adv Mater 2023; 35:e2210562. [PMID: 36739113 DOI: 10.1002/adma.202210562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/06/2023] [Indexed: 05/17/2023]
Abstract
Despite extensive studies on size effects in ferroelectrics, how structures and properties evolve in antiferroelectrics with reduced dimensions still remains elusive. Given the enormous potential of utilizing antiferroelectrics for high-energy-density storage applications, understanding their size effects will provide key information for optimizing device performances at small scales. Here, the fundamental intrinsic size dependence of antiferroelectricity in lead-free NaNbO3 membranes is investigated. Via a wide range of experimental and theoretical approaches, an intriguing antiferroelectric-to-ferroelectric transition upon reducing membrane thickness is probed. This size effect leads to a ferroelectric single-phase below 40 nm, as well as a mixed-phase state with ferroelectric and antiferroelectric orders coexisting above this critical thickness. Furthermore, it is shown that the antiferroelectric and ferroelectric orders are electrically switchable. First-principle calculations further reveal that the observed transition is driven by the structural distortion arising from the membrane surface. This work provides direct experimental evidence for intrinsic size-driven scaling in antiferroelectrics and demonstrates enormous potential of utilizing size effects to drive emergent properties in environmentally benign lead-free oxides with the membrane platform.
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Affiliation(s)
- Ruijuan Xu
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27606, USA
| | - Kevin J Crust
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
| | - Varun Harbola
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
| | - Rémi Arras
- CEMES, Université de Toulouse, CNRS, UPS, 29 rue Jeanne Marvig, F-31055, Toulouse, France
| | - Kinnary Y Patel
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Sergey Prosandeev
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Hui Cao
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Yu-Tsun Shao
- Department of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, 90089, USA
| | - Piush Behera
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Lucas Caretta
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
- School of Engineering, Brown University, Providence, RI, 02912, USA
| | - Woo Jin Kim
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Aarushi Khandelwal
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Megha Acharya
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Melody M Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Yin Liu
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27606, USA
| | - Edward S Barnard
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Archana Raja
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Lane W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - X Wendy Gu
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Hua Zhou
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Ramamoorthy Ramesh
- Department of Materials Science and Nanoengineering, Department of Physics and Astronomy, Rice University, Houston, TX, 77251, USA
| | - David A Muller
- Department of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
| | - Laurent Bellaiche
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Harold Y Hwang
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
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12
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Kim WJ, Smeaton MA, Jia C, Goodge BH, Cho BG, Lee K, Osada M, Jost D, Ievlev AV, Moritz B, Kourkoutis LF, Devereaux TP, Hwang HY. Geometric frustration of Jahn-Teller order in the infinite-layer lattice. Nature 2023; 615:237-243. [PMID: 36813969 DOI: 10.1038/s41586-022-05681-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 12/22/2022] [Indexed: 02/24/2023]
Abstract
The Jahn-Teller effect, in which electronic configurations with energetically degenerate orbitals induce lattice distortions to lift this degeneracy, has a key role in many symmetry-lowering crystal deformations1. Lattices of Jahn-Teller ions can induce a cooperative distortion, as exemplified by LaMnO3 (refs. 2,3). Although many examples occur in octahedrally4 or tetrahedrally5 coordinated transition metal oxides due to their high orbital degeneracy, this effect has yet to be manifested for square-planar anion coordination, as found in infinite-layer copper6,7, nickel8,9, iron10,11 and manganese oxides12. Here we synthesize single-crystal CaCoO2 thin films by topotactic reduction of the brownmillerite CaCoO2.5 phase. We observe a markedly distorted infinite-layer structure, with ångström-scale displacements of the cations from their high-symmetry positions. This can be understood to originate from the Jahn-Teller degeneracy of the dxz and dyz orbitals in the d7 electronic configuration along with substantial ligand-transition metal mixing. A complex pattern of distortions arises in a [Formula: see text] tetragonal supercell, reflecting the competition between an ordered Jahn-Teller effect on the CoO2 sublattice and the geometric frustration of the associated displacements of the Ca sublattice, which are strongly coupled in the absence of apical oxygen. As a result of this competition, the CaCoO2 structure forms an extended two-in-two-out type of Co distortion following 'ice rules'13.
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Affiliation(s)
- Woo Jin Kim
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA. .,Department of Applied Physics, Stanford University, Stanford, CA, USA.
| | - Michelle A Smeaton
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA
| | - Chunjing Jia
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.,Department of Physics, University of Florida, Gainesville, FL, USA
| | - Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Byeong-Gwan Cho
- Pohang Accelerator Laboratory, POSTECH, Pohang, Republic of Korea
| | - Kyuho Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.,Department of Physics, Stanford University, Stanford, CA, USA
| | - Motoki Osada
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.,Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Daniel Jost
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Anton V Ievlev
- Center for Nanophase Materials Sciences Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Brian Moritz
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Thomas P Devereaux
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.,Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA. .,Department of Applied Physics, Stanford University, Stanford, CA, USA.
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13
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Zhou J, Wu Y, Kwon H, Li Y, Xiao X, Ye Y, Ma Y, Goodson KE, Hwang HY, Cui Y. Heat Conductor-Insulator Transition in Electrochemically Controlled Hybrid Superlattices. Nano Lett 2022; 22:5443-5450. [PMID: 35715219 DOI: 10.1021/acs.nanolett.2c01407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Designing materials with ultralow thermal conductivity has broad technological impact, from thermal protection to energy harvesting. Low thermal conductivity is commonly observed in anharmonic and strongly disordered materials, yet a microscopic understanding of the correlation to atomic motion is often lacking. Here we report that molecular insertion into an existing two-dimensional layered lattice structure creates a hybrid superlattice with extremely low thermal conductivity. Vibrational characterization and ab initio molecular dynamics simulations reveal strong damping of transverse acoustic waves and significant softening of longitudinal vibrations. Together with spectral correlation analysis, we demonstrate that the molecular insertion creates liquid-like atomic motion in the existing lattice framework, causing a large suppression of heat conduction. The hybrid materials can be transformed into solution-processable coatings and used for thermal protection in wearable electronics. Our work provides a generic mechanism for the design of heat insulators and may further facilitate the engineering of heat conduction based on understanding atomic correlations.
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Affiliation(s)
- Jiawei Zhou
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Yecun Wu
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | | | - Yanbin Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | | | - Yusheng Ye
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | | | | | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Yi Cui
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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14
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Wu Y, Wang J, Li Y, Zhou J, Wang BY, Yang A, Wang LW, Hwang HY, Cui Y. Observation of an intermediate state during lithium intercalation of twisted bilayer MoS 2. Nat Commun 2022; 13:3008. [PMID: 35637182 PMCID: PMC9151788 DOI: 10.1038/s41467-022-30516-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 02/24/2022] [Indexed: 11/22/2022] Open
Abstract
Lithium intercalation of MoS2 is generally believed to introduce a phase transition from H phase (semiconducting) to T phase (metallic). However, during the intercalation process, a spatially sharp boundary is usually formed between the fully intercalated T phase MoS2 and non-intercalated H phase MoS2. The intermediate state, i.e., lightly intercalated H phase MoS2 without a phase transition, is difficult to investigate by optical-microscope-based spectroscopy due to the narrow size. Here, we report the stabilization of the intermediate state across the whole flake of twisted bilayer MoS2. The twisted bilayer system allows the lithium to intercalate from the top surface and enables fast Li-ion diffusion by the reduced interlayer interaction. The E2g Raman mode of the intermediate state shows a peak splitting behavior. Our simulation results indicate that the intermediate state is stabilized by lithium-induced symmetry breaking of the H phase MoS2. Our results provide an insight into the non-uniform intercalation during battery charging and discharging, and also open a new opportunity to modulate the properties of twisted 2D systems with guest species doping in the Moiré structures.
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Affiliation(s)
- Yecun Wu
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Jingyang Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
- Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, CA, USA
| | - Yanbin Li
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Jiawei Zhou
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Ankun Yang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Lin-Wang Wang
- Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, CA, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
- Department of Applied Physics, Stanford University, Stanford, CA, USA.
| | - Yi Cui
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA.
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15
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Goodge BH, El Baggari I, Hong SS, Wang Z, Schlom DG, Hwang HY, Kourkoutis LF. Disentangling Coexisting Structural Order Through Phase Lock-In Analysis of Atomic-Resolution STEM Data. Microsc Microanal 2022; 28:1-8. [PMID: 35190012 DOI: 10.1017/s1431927622000125] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
As a real-space technique, atomic-resolution STEM imaging contains both amplitude and geometric phase information about structural order in materials, with the latter encoding important information about local variations and heterogeneities present in crystalline lattices. Such phase information can be extracted using geometric phase analysis (GPA), a method which has generally focused on spatially mapping elastic strain. Here we demonstrate an alternative phase demodulation technique and its application to reveal complex structural phenomena in correlated quantum materials. As with other methods of image phase analysis, the phase lock-in approach can be implemented to extract detailed information about structural order and disorder, including dislocations and compound defects in crystals. Extending the application of this phase analysis to Fourier components that encode periodic modulations of the crystalline lattice, such as superlattice or secondary frequency peaks, we extract the behavior of multiple distinct order parameters within the same image, yielding insights into not only the crystalline heterogeneity but also subtle emergent order parameters such as antipolar displacements. When applied to atomic-resolution images spanning large (~0.5 × 0.5 μm2) fields of view, this approach enables vivid visualizations of the spatial interplay between various structural orders in novel materials.
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Affiliation(s)
- Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY14853, USA
| | | | - Seung Sae Hong
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA94025, USA
| | - Zhe Wang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY14853, USA
| | - Darrell G Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY14853, USA
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA94025, USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY14853, USA
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16
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Lee JM, Hwang SH, Lee KB, Byun JI, Hwang HY. Standardization of 129I using the movable 4πβ(LS)-X(NaI(Tl)) system. Appl Radiat Isot 2021; 179:110022. [PMID: 34781075 DOI: 10.1016/j.apradiso.2021.110022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 10/13/2021] [Accepted: 11/05/2021] [Indexed: 11/28/2022]
Abstract
The 129I standardization, using the movable 4πβ(LS)-X(NaI(Tl)) coincidence system, was performed for two 129I radioactive sources - one was dissolved in 0.1M NaOH solution and the other in 0.1M HNO3 solution. The system incorporates three movable PM tubes for a β-counter placed on a plane and a X-ray detector that can be moved up to the bottom of the vial. The β-efficiency depending on the amount of radioactive solution was investigated with 14 liquid scintillation samples prepared by gravimetrically dispensing 4.4-145 mg of 129I radioactive solution. The β-efficiencies above 90% were observed at less than 56 mg, but it was at most 70% at 145 mg. This occurred regardless of the activity of the sample or the type of chemical solution used to dissolve 129I source. The activity concentration of each 129I source was determined by efficiency-extrapolation method for samples with an activity range of 0.28-4.5 kBq. The β-efficiency points were derived over 10 intervals by moving 3-PM tubes in fine steps of about 1 mm from the sample. The highest value for β-efficiency was 95%. The combined uncertainty were 0.25% and 0.26%, respectively. The stated precision obtained using the system is better than that previously reported in the literature obtained by the triple to double coincidence ratio (TDCR) or the CIEMAT/NIST efficiency tracing method.
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Affiliation(s)
- J M Lee
- Korea Research Institute of Standards and Science, Gajeong-ro, Yuseong-gu, Daejeon, 267, South Korea
| | - S H Hwang
- Korea Research Institute of Standards and Science, Gajeong-ro, Yuseong-gu, Daejeon, 267, South Korea
| | - K B Lee
- Korea Research Institute of Standards and Science, Gajeong-ro, Yuseong-gu, Daejeon, 267, South Korea
| | - J I Byun
- Korea Institute of Nuclear Safety, Gwahak-ro, Yuseong-gu, Daejeon, 62, South Korea
| | - H Y Hwang
- Korea Research Institute of Standards and Science, Gajeong-ro, Yuseong-gu, Daejeon, 267, South Korea.
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17
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Osada M, Wang BY, Goodge BH, Harvey SP, Lee K, Li D, Kourkoutis LF, Hwang HY. Nickelate Superconductivity without Rare-Earth Magnetism: (La,Sr)NiO 2. Adv Mater 2021; 33:e2104083. [PMID: 34536042 DOI: 10.1002/adma.202104083] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 08/17/2021] [Indexed: 06/13/2023]
Abstract
The occurrence of unconventional superconductivity in cuprates has long motivated the search for manifestations in other layered transition metal oxides. Recently, superconductivity is found in infinite-layer nickelate (Nd,Sr)NiO2 and (Pr,Sr)NiO2 thin films, formed by topotactic reduction from the perovskite precursor phase. A topic of much current interest is whether rare-earth moments are essential for superconductivity in this system. In this study, it is found that with significant materials optimization, substantial portions of the La1- x Srx NiO2 phase diagram can enter the regime of coherent low-temperature transport (x = 0.14 - 0.20), with subsequent superconducting transitions and a maximum onset of ≈9 K at x = 0.20. Additionally, the unexpected indication of a superconducting ground state in undoped LaNiO2 is observed, which likely reflects the self-doped nature of the electronic structure. Combining the results of (La/Pr/Nd)1- x Srx NiO2 reveals a generalized superconducting dome, characterized by systematic shifts in the unit cell volume and in the relative electron-hole populations across the lanthanides.
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Affiliation(s)
- Motoki Osada
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
| | - Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, 14853, USA
| | - Shannon P Harvey
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Kyuho Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
| | - Danfeng Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, 14853, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
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18
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El Baggari I, Baek DJ, Zachman MJ, Lu D, Hikita Y, Hwang HY, Nowadnick EA, Kourkoutis LF. Charge order textures induced by non-linear couplings in a half-doped manganite. Nat Commun 2021; 12:3747. [PMID: 34145244 PMCID: PMC8213702 DOI: 10.1038/s41467-021-24026-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 05/28/2021] [Indexed: 11/13/2022] Open
Abstract
The self-organization of strongly interacting electrons into superlattice structures underlies the properties of many quantum materials. How these electrons arrange within the superlattice dictates what symmetries are broken and what ground states are stabilized. Here we show that cryogenic scanning transmission electron microscopy (cryo-STEM) enables direct mapping of local symmetries and order at the intra-unit-cell level in the model charge-ordered system Nd1/2Sr1/2MnO3. In addition to imaging the prototypical site-centered charge order, we discover the nanoscale coexistence of an exotic intermediate state which mixes site and bond order and breaks inversion symmetry. We further show that nonlinear coupling of distinct lattice modes controls the selection between competing ground states. The results demonstrate the importance of lattice coupling for understanding and manipulating the character of electronic self-organization and that cryo-STEM can reveal local order in strongly correlated systems at the atomic scale. In this paper, the authors demonstrate that cryogenic scanning transmission electron microscopy allows for the direct mapping of the local arrangements and symmetries of electronic order, providing a useful method for studying strongly correlated systems. They show this using the example of Nd1/2Sr1/2MnO3, a model charge ordered material.
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Affiliation(s)
| | - David J Baek
- School of Electrical and Computer Engineering, Cornell University, Ithaca, NY, USA.,Intel Corp., Hillsboro, OR, USA
| | - Michael J Zachman
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Di Lu
- Department of Physics, Stanford University, Stanford, CA, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.,Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.,Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.,Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Elizabeth A Nowadnick
- Department of Materials Science and Engineering, University of California Merced, Merced, CA, USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA. .,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA.
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19
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Li D, Adamo C, Wang BY, Yoon H, Chen Z, Hong SS, Lu D, Cui Y, Hikita Y, Hwang HY. Stabilization of Sr 3Al 2O 6 Growth Templates for Ex Situ Synthesis of Freestanding Crystalline Oxide Membranes. Nano Lett 2021; 21:4454-4460. [PMID: 33989008 DOI: 10.1021/acs.nanolett.1c01194] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A new synthetic approach has recently been developed for the fabrication of freestanding crystalline perovskite oxide nanomembranes, which involves the epitaxial growth of a water-soluble sacrificial layer. By utilizing an ultrathin capping layer of SrTiO3, here we show that this sacrificial layer, as grown by pulsed laser deposition, can be stabilized in air and therefore be used as transferrable templates for ex situ epitaxial growth using other techniques. We find that the stability of these templates depends on the thickness of the capping layer. On these templates, freestanding superconducting SrTiO3 membranes were synthesized ex situ using molecular beam epitaxy, enabled by the lower growth temperature which preserves the sacrificial layer. This study paves the way for the synthesis of an expanded selection of freestanding oxide membranes and heterostructures with a wide variety of ex situ growth techniques.
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Affiliation(s)
- Danfeng Li
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Carolina Adamo
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
| | - Bai Yang Wang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
| | - Hyeok Yoon
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
| | - Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
| | - Seung Sae Hong
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Di Lu
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
| | - Yi Cui
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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20
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Lee JM, Agung A, Hwang SH, Lee KB, Hwang HY. Development of a movable 4πβ(LS)-γ coincidence counting system for activity standardization of β-γ emitters. Appl Radiat Isot 2021; 174:109743. [PMID: 33915348 DOI: 10.1016/j.apradiso.2021.109743] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 12/23/2020] [Accepted: 04/20/2021] [Indexed: 11/30/2022]
Abstract
A new movable 3PM-γ coincidence system, based on 4πβ(LS)-γ coincidence counting, for activity measurement of β-γ emitters has been designed at the Korea Research Institute of Standards and Science (KRISS). The system incorporates 3 PM tubes on the plane and two detectors placed above and below the center of the plane. The 3 PM tubes for β-counters in the plane are movable up to 100 mm from a liquid scintillation vial, thus enabling the variation of β-detection efficiencies by a geometrical technique. A NaI(Tl) γ-counter was set above for the present work. The β-event is determined by counting the logical sum of three double coincidences. All the necessary electronics, i.e., logical sum, adjusting the duration of dead-time of each counting channel and coincidence resolving times, and analyzing coincidence relation, were specially designed to be fabricated in an integrated circuit. Details of the detectors, the electronics, the overall movable 3PM-γ coincidence system are presented, as well as the results of investigations to assess its operating characteristics. Validation measurements have been performed with 60Co and 57Co sources. The highest β-detection efficiency achieved with 60Co and 57Co was 97% and 95%, respectively. The activity concentration determined with a new system agreed with calibrated values within the uncertainty range. Further results from validation measurements and the corresponding uncertainty budgets are presented.
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Affiliation(s)
- J M Lee
- Korea Research Institute of Standards and Science, Gajeong-ro, Yuseong-gu, Daejeon, 267, South Korea
| | - A Agung
- Korea Research Institute of Standards and Science, Gajeong-ro, Yuseong-gu, Daejeon, 267, South Korea
| | - S H Hwang
- Korea Research Institute of Standards and Science, Gajeong-ro, Yuseong-gu, Daejeon, 267, South Korea
| | - K B Lee
- Korea Research Institute of Standards and Science, Gajeong-ro, Yuseong-gu, Daejeon, 267, South Korea
| | - H Y Hwang
- Mokwon University, Doanbuk-ro, Seo-gu, Daejeon, 88, South Korea.
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21
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Harbola V, Crossley S, Hong SS, Lu D, Birkhölzer YA, Hikita Y, Hwang HY. Strain Gradient Elasticity in SrTiO 3 Membranes: Bending versus Stretching. Nano Lett 2021; 21:2470-2475. [PMID: 33689379 DOI: 10.1021/acs.nanolett.0c04787] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Young's modulus determines the mechanical loads required to elastically stretch a material and also the loads required to bend it, given that bending stretches one surface while compressing the opposite one. Flexoelectric materials have the additional property of becoming electrically polarized when bent. The associated energy cost can additionally contribute to elasticity via strain gradients, particularly at small length scales where they are geometrically enhanced. Here, we present nanomechanical measurements of freely suspended SrTiO3 crystalline membrane drumheads. We observe an unexpected nonmonotonic thickness dependence of Young's modulus upon small deflections. Furthermore, the modulus inferred from a predominantly bending deformation is three times larger than that of a predominantly stretching deformation for membranes thinner than 20 nm. In this regime we extract a strain gradient elastic coupling of ∼2.2 μN, which could be used in new operational regimes of nanoelectro-mechanics.
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Affiliation(s)
- Varun Harbola
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Samuel Crossley
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Seung Sae Hong
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Di Lu
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Yorick A Birkhölzer
- Department of Inorganic Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
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22
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Rischau CW, Li Y, Fauqué B, Inoue H, Kim M, Bell C, Hwang HY, Kapitulnik A, Behnia K. Universal Bound to the Amplitude of the Vortex Nernst Signal in Superconductors. Phys Rev Lett 2021; 126:077001. [PMID: 33666461 DOI: 10.1103/physrevlett.126.077001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/05/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
A liquid of superconducting vortices generates a transverse thermoelectric response. This Nernst signal has a tail deep in the normal state due to superconducting fluctuations. Here, we present a study of the Nernst effect in two-dimensional heterostructures of Nb-doped strontium titanate (STO) and in amorphous MoGe. The Nernst signal generated by ephemeral Cooper pairs above the critical temperature has the magnitude expected by theory in STO. On the other hand, the peak amplitude of the vortex Nernst signal below T_{c} is comparable in both and in numerous other superconductors despite the large distribution of the critical temperature and the critical magnetic fields. In four superconductors belonging to different families, the maximum Nernst signal corresponds to an entropy per vortex per layer of ≈k_{B}ln2.
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Affiliation(s)
- Carl Willem Rischau
- Laboratoire de Physique et d'Étude des Matériaux (ESPCI Paris-CNRS-Sorbonne Université), PSL Research University, 75005 Paris, France
| | - Yuke Li
- Laboratoire de Physique et d'Étude des Matériaux (ESPCI Paris-CNRS-Sorbonne Université), PSL Research University, 75005 Paris, France
| | - Benoît Fauqué
- JEIP, USR 3573 CNRS, Collège de France, PSL Research University, 75005 Paris, France
| | - Hisashi Inoue
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Minu Kim
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Christopher Bell
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Aharon Kapitulnik
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Kamran Behnia
- Laboratoire de Physique et d'Étude des Matériaux (ESPCI Paris-CNRS-Sorbonne Université), PSL Research University, 75005 Paris, France
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23
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Pesquera D, Parsonnet E, Qualls A, Xu R, Gubser AJ, Kim J, Jiang Y, Velarde G, Huang YL, Hwang HY, Ramesh R, Martin LW. Beyond Substrates: Strain Engineering of Ferroelectric Membranes. Adv Mater 2020; 32:e2003780. [PMID: 32964567 DOI: 10.1002/adma.202003780] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 08/19/2020] [Indexed: 06/11/2023]
Abstract
Strain engineering in perovskite oxides provides for dramatic control over material structure, phase, and properties, but is restricted by the discrete strain states produced by available high-quality substrates. Here, using the ferroelectric BaTiO3 , production of precisely strain-engineered, substrate-released nanoscale membranes is demonstrated via an epitaxial lift-off process that allows the high crystalline quality of films grown on substrates to be replicated. In turn, fine structural tuning is achieved using interlayer stress in symmetric trilayer oxide-metal/ferroelectric/oxide-metal structures fabricated from the released membranes. In devices integrated on silicon, the interlayer stress provides deterministic control of ordering temperature (from 75 to 425 °C) and releasing the substrate clamping is shown to dramatically impact ferroelectric switching and domain dynamics (including reducing coercive fields to <10 kV cm-1 and improving switching times to <5 ns for a 20 µm diameter capacitor in a 100-nm-thick film). In devices integrated on flexible polymers, enhanced room-temperature dielectric permittivity with large mechanical tunability (a 90% change upon ±0.1% strain application) is demonstrated. This approach paves the way toward the fabrication of ultrafast CMOS-compatible ferroelectric memories and ultrasensitive flexible nanosensor devices, and it may also be leveraged for the stabilization of novel phases and functionalities not achievable via direct epitaxial growth.
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Affiliation(s)
- David Pesquera
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Spain
| | - Eric Parsonnet
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Alexander Qualls
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Ruijuan Xu
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Andrew J Gubser
- Department of Nuclear Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Jieun Kim
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Yizhe Jiang
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Gabriel Velarde
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Yen-Lin Huang
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Harold Y Hwang
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Lane W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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24
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Hepting M, Li D, Jia CJ, Lu H, Paris E, Tseng Y, Feng X, Osada M, Been E, Hikita Y, Chuang YD, Hussain Z, Zhou KJ, Nag A, Garcia-Fernandez M, Rossi M, Huang HY, Huang DJ, Shen ZX, Schmitt T, Hwang HY, Moritz B, Zaanen J, Devereaux TP, Lee WS. Publisher Correction: Electronic structure of the parent compound of superconducting infinite-layer nickelates. Nat Mater 2020; 19:1036. [PMID: 32661388 DOI: 10.1038/s41563-020-0761-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Affiliation(s)
- M Hepting
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - D Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - C J Jia
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
| | - H Lu
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - E Paris
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - Y Tseng
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - X Feng
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - M Osada
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - E Been
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Y Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Y-D Chuang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Z Hussain
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - K J Zhou
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - A Nag
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | | | - M Rossi
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - H Y Huang
- NSRRC, Hsinchu Science Park, Hsinchu, Taiwan
| | - D J Huang
- NSRRC, Hsinchu Science Park, Hsinchu, Taiwan
| | - Z X Shen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA, USA
| | - T Schmitt
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - H Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - B Moritz
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - J Zaanen
- Instituut-Lorentz for theoretical Physics, Leiden University, Leiden, the Netherlands
| | - T P Devereaux
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - W S Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
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25
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Kim KH, Späh A, Pathak H, Yang C, Bonetti S, Amann-Winkel K, Mariedahl D, Schlesinger D, Sellberg JA, Mendez D, van der Schot G, Hwang HY, Clark J, Shigeki O, Tadashi T, Harada Y, Ogasawara H, Katayama T, Nilsson A, Perakis F. Anisotropic X-Ray Scattering of Transiently Oriented Water. Phys Rev Lett 2020; 125:076002. [PMID: 32857536 DOI: 10.1103/physrevlett.125.076002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
We study the structural dynamics of liquid water by time-resolved anisotropic x-ray scattering under the optical Kerr effect condition. In this way, we can separate the anisotropic scattering decay of 160 fs from the delayed temperature increase of ∼0.1 K occurring at 1 ps and quantify transient changes in the O-O pair distribution function. Polarizable molecular dynamics simulations reproduce well the experiment, indicating transient alignment of molecules along the electric field, which shortens the nearest-neighbor distances. In addition, analysis of the simulated water local structure provides evidence that two hypothesized fluctuating water configurations exhibit different polarizability.
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Affiliation(s)
- Kyung Hwan Kim
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
- Department of Chemistry, POSTECH, Pohang 37673, Republic of Korea
| | - Alexander Späh
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
| | - Harshad Pathak
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
| | - Cheolhee Yang
- Department of Chemistry, POSTECH, Pohang 37673, Republic of Korea
| | - Stefano Bonetti
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, 30172 Venice-Mestre, Italy
| | - Katrin Amann-Winkel
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
| | - Daniel Mariedahl
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
| | - Daniel Schlesinger
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
- Department of Environmental Science and Bolin Centre for Climate Research, Stockholm University, 114 18 Stockholm, Sweden
| | - Jonas A Sellberg
- Biomedical and X-Ray Physics, Department of Applied Physics, AlbaNova University Center, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Derek Mendez
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Gijs van der Schot
- Department of Cell and Molecular Biology, Laboratory of Molecular Biophysics, Uppsala University, SE-75124 Uppsala, Sweden
| | - Harold Y Hwang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jesse Clark
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Owada Shigeki
- Japan Synchrotron Radiation Research Institute, Kouto 1-1-1, Sayo, Hyogo 679-5198, Japan
| | - Togashi Tadashi
- Japan Synchrotron Radiation Research Institute, Kouto 1-1-1, Sayo, Hyogo 679-5198, Japan
| | - Yoshihisa Harada
- Institute for Solid State Physics, The University of Tokyo, Kouto 1-1-1, Sayo, Hyogo 679-5148, Japan
| | | | - Tetsuo Katayama
- Japan Synchrotron Radiation Research Institute, Kouto 1-1-1, Sayo, Hyogo 679-5198, Japan
| | - Anders Nilsson
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
| | - Fivos Perakis
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
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26
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Osada M, Wang BY, Goodge BH, Lee K, Yoon H, Sakuma K, Li D, Miura M, Kourkoutis LF, Hwang HY. A Superconducting Praseodymium Nickelate with Infinite Layer Structure. Nano Lett 2020; 20:5735-5740. [PMID: 32574061 DOI: 10.1021/acs.nanolett.0c01392] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A variety of nickel oxide compounds have long been studied for their manifestation of various correlated electron phenomena. Recently, superconductivity was observed in nanoscale infinite layer nickelate thin films of Nd0.8Sr0.2NiO2, epitaxially stabilized on SrTiO3 substrates via topotactic reduction from the perovskite precursor phase. Here, we present the synthesis and properties of PrNiO2 thin films on SrTiO3. Upon doping in Pr0.8Sr0.2NiO2, we observe superconductivity with a transition temperature of 7-12 K and robust critical current density at 2 K of 334 kA/cm2. These findings indicate that superconductivity in the infinite layer nickelates is relatively insensitive to the details of the rare earth 4f configuration. Furthermore, they motivate the exploration of a broader family of compounds based on two-dimensional NiO2 planes, which will enable systematic investigation of the superconducting and normal state properties and their underlying mechanisms.
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Affiliation(s)
- Motoki Osada
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
| | - Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
| | - Kyuho Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, Stanford University, Stanford, California 94305, United States
| | - Hyeok Yoon
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Keita Sakuma
- Graduate School of Science & Technology, Seikei University, Musashino, Tokyo 180-8633, Japan
| | - Danfeng Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Masashi Miura
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
- Graduate School of Science & Technology, Seikei University, Musashino, Tokyo 180-8633, Japan
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
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27
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Li D, Wang BY, Lee K, Harvey SP, Osada M, Goodge BH, Kourkoutis LF, Hwang HY. Superconducting Dome in Nd_{1-x}Sr_{x}NiO_{2} Infinite Layer Films. Phys Rev Lett 2020; 125:027001. [PMID: 32701320 DOI: 10.1103/physrevlett.125.027001] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
We report the phase diagram of Nd_{1-x}Sr_{x}NiO_{2} infinite layer thin films grown on SrTiO_{3}. A superconducting dome spanning 0.125<x<0.25 is found, remarkably similar to cuprates, albeit over a narrower doping window. However, while cuprate superconductivity is bounded by an insulator for underdoping and a metal for overdoping, here we observe weakly insulating behavior on either side of the dome. Furthermore, the normal state Hall coefficient is always small and proximate to a continuous zero crossing in doping and in temperature, in contrast to the ∼1/x dependence observed for cuprates. This suggests the presence of both electronlike and holelike bands, consistent with band structure calculations.
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Affiliation(s)
- Danfeng Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Kyuho Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Shannon P Harvey
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Motoki Osada
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
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28
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Hong SS, Gu M, Verma M, Harbola V, Wang BY, Lu D, Vailionis A, Hikita Y, Pentcheva R, Rondinelli JM, Hwang HY. Extreme tensile strain states in La
0.7
Ca
0.3
MnO
3
membranes. Science 2020; 368:71-76. [DOI: 10.1126/science.aax9753] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 03/09/2020] [Indexed: 11/02/2022]
Affiliation(s)
- Seung Sae Hong
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Materials Science and Engineering, University of California, Davis, CA 95616, USA
| | - Mingqiang Gu
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Manish Verma
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47053 Duisburg, Germany
| | - Varun Harbola
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Di Lu
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Arturas Vailionis
- Stanford Nano Shared Facilities, Stanford University, Stanford, CA 94305, USA
- Department of Physics, Kaunas University of Technology, LT-51368 Kaunas, Lithuania
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Rossitza Pentcheva
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47053 Duisburg, Germany
| | - James M. Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Harold Y. Hwang
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
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29
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Hepting M, Li D, Jia CJ, Lu H, Paris E, Tseng Y, Feng X, Osada M, Been E, Hikita Y, Chuang YD, Hussain Z, Zhou KJ, Nag A, Garcia-Fernandez M, Rossi M, Huang HY, Huang DJ, Shen ZX, Schmitt T, Hwang HY, Moritz B, Zaanen J, Devereaux TP, Lee WS. Electronic structure of the parent compound of superconducting infinite-layer nickelates. Nat Mater 2020; 19:381-385. [PMID: 31959951 DOI: 10.1038/s41563-019-0585-z] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/11/2019] [Indexed: 05/21/2023]
Abstract
The search continues for nickel oxide-based materials with electronic properties similar to cuprate high-temperature superconductors1-10. The recent discovery of superconductivity in the doped infinite-layer nickelate NdNiO2 (refs. 11,12) has strengthened these efforts. Here, we use X-ray spectroscopy and density functional theory to show that the electronic structure of LaNiO2 and NdNiO2, while similar to the cuprates, includes significant distinctions. Unlike cuprates, the rare-earth spacer layer in the infinite-layer nickelate supports a weakly interacting three-dimensional 5d metallic state, which hybridizes with a quasi-two-dimensional, strongly correlated state with [Formula: see text] symmetry in the NiO2 layers. Thus, the infinite-layer nickelate can be regarded as a sibling of the rare-earth intermetallics13-15, which are well known for heavy fermion behaviour, where the NiO2 correlated layers play an analogous role to the 4f states in rare-earth heavy fermion compounds. This Kondo- or Anderson-lattice-like 'oxide-intermetallic' replaces the Mott insulator as the reference state from which superconductivity emerges upon doping.
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Affiliation(s)
- M Hepting
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - D Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - C J Jia
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
| | - H Lu
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - E Paris
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - Y Tseng
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - X Feng
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - M Osada
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - E Been
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Y Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Y-D Chuang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Z Hussain
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - K J Zhou
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - A Nag
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | | | - M Rossi
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - H Y Huang
- NSRRC, Hsinchu Science Park, Hsinchu, Taiwan
| | - D J Huang
- NSRRC, Hsinchu Science Park, Hsinchu, Taiwan
| | - Z X Shen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA, USA
| | - T Schmitt
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - H Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - B Moritz
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - J Zaanen
- Instituut-Lorentz for theoretical Physics, Leiden University, Leiden, the Netherlands
| | - T P Devereaux
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - W S Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
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30
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Yang A, Zhou G, Kong X, Vilá RA, Pei A, Wu Y, Yu X, Zheng X, Wu CL, Liu B, Chen H, Xu Y, Chen D, Li Y, Fakra S, Hwang HY, Qin J, Chu S, Cui Y. Electrochemical generation of liquid and solid sulfur on two-dimensional layered materials with distinct areal capacities. Nat Nanotechnol 2020; 15:231-237. [PMID: 31988508 DOI: 10.1038/s41565-019-0624-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 12/12/2019] [Indexed: 05/14/2023]
Abstract
It has recently been shown that sulfur, a solid material in its elementary form S8, can stay in a supercooled state as liquid sulfur in an electrochemical cell. We establish that this newly discovered state could have implications for lithium-sulfur batteries. Here, through in situ studies of electrochemical sulfur generation, we show that liquid (supercooled) and solid elementary sulfur possess very different areal capacities over the same charging period. To control the physical state of sulfur, we studied its growth on two-dimensional layered materials. We found that on the basal plane, only liquid sulfur accumulates; by contrast, at the edge sites, liquid sulfur accumulates if the thickness of the two-dimensional material is small, whereas solid sulfur nucleates if the thickness is large (tens of nanometres). Correlating the sulfur states with their respective areal capacities, as well as controlling the growth of sulfur on two-dimensional materials, could provide insights for the design of future lithium-sulfur batteries.
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Affiliation(s)
- Ankun Yang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Guangmin Zhou
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Xian Kong
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Rafael A Vilá
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Allen Pei
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Yecun Wu
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Xiaoyun Yu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Xueli Zheng
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Chun-Lan Wu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Bofei Liu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Hao Chen
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Yan Xu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Di Chen
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
- The Future Laboratory, Tsinghua University, Beijing, China
| | - Yanxi Li
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Sirine Fakra
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Harold Y Hwang
- Department of Applied Physics, Stanford University, Stanford, CA, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Jian Qin
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Steven Chu
- Department of Physics, Stanford University, Stanford, CA, USA
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
| | - Yi Cui
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA.
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
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31
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Zhou G, Yang A, Wang Y, Gao G, Pei A, Yu X, Zhu Y, Zong L, Liu B, Xu J, Liu N, Zhang J, Li Y, Wang LW, Hwang HY, Brongersma ML, Chu S, Cui Y. Electrotunable liquid sulfur microdroplets. Nat Commun 2020; 11:606. [PMID: 32001696 PMCID: PMC6992759 DOI: 10.1038/s41467-020-14438-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 12/15/2019] [Indexed: 11/08/2022] Open
Abstract
Manipulating liquids with tunable shape and optical functionalities in real time is important for electroactive flow devices and optoelectronic devices, but remains a great challenge. Here, we demonstrate electrotunable liquid sulfur microdroplets in an electrochemical cell. We observe electrowetting and merging of sulfur droplets under different potentiostatic conditions, and successfully control these processes via selective design of sulfiphilic/sulfiphobic substrates. Moreover, we employ the electrowetting phenomena to create a microlens based on the liquid sulfur microdroplets and tune its characteristics in real time through changing the shape of the liquid microdroplets in a fast, repeatable, and controlled manner. These studies demonstrate a powerful in situ optical battery platform for unraveling the complex reaction mechanism of sulfur chemistries and for exploring the rich material properties of the liquid sulfur, which shed light on the applications of liquid sulfur droplets in devices such as microlenses, and potentially other electrotunable and optoelectronic devices.
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Affiliation(s)
- Guangmin Zhou
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute & Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Ankun Yang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Yifei Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Guoping Gao
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Allen Pei
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Xiaoyun Yu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Yangying Zhu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Linqi Zong
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Bofei Liu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Jinwei Xu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Nian Liu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Jinsong Zhang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Yanxi Li
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Lin-Wang Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Harold Y Hwang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Mark L Brongersma
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Steven Chu
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, 94303, USA
| | - Yi Cui
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA.
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA.
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32
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Kim BSY, Hikita Y, Yajima T, Hwang HY. Heteroepitaxial vertical perovskite hot-electron transistors down to the monolayer limit. Nat Commun 2019; 10:5312. [PMID: 31757949 PMCID: PMC6874601 DOI: 10.1038/s41467-019-13290-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 10/25/2019] [Indexed: 12/04/2022] Open
Abstract
Two-dimensional heterostructures combined with vertical geometries are candidates to probe and utilize the physical properties of atomically-thin materials. The vertical configuration enables a unique form of hot-carrier spectroscopy as well as atomic-scale devices. Here, we present the room-temperature evolution of heteroepitaxial perovskite hot-electron transistors using a SrRuO3 base down to the monolayer limit (∼4 Å). As a fundamental electronic probe, we observe an abrupt transition in the hot-electron mean free path as a function of base thickness, coinciding with the thickness-dependent resistive transition. As a path towards devices, we demonstrate the integrated synthesis of perovskite one-dimensional electrical edge contacts using water-soluble and growth-compatible Sr3Al2O6 hard masks. Edge-contacted monolayer-base transistors exhibit on/off ratios reaching ∼108, complete electrostatic screening by the base manifesting pure hot-electron injection, and excellent scaling of the output current density with device dimensions. These results open new avenues for incorporating emergent phenomena at oxide interfaces and in heterostructures. Two-dimensional heterostructures combined with vertical geometries trigger superior functionalities in fundamental studies and applications. Here, the authors report vertical perovskite hot-electron transistors integrated with perovskite one-dimensional edge contacts down to the monolayer limit.
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Affiliation(s)
- Brian S Y Kim
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA. .,Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Takeaki Yajima
- Department of Materials Engineering, The University of Tokyo, Bunkyo, Tokyo, 113-8656, Japan
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA. .,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
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33
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Pein BC, Lee CK, Shi L, Shi J, Chang W, Hwang HY, Scherer J, Coropceanu I, Zhao X, Zhang X, Bulović V, Bawendi MG, Willard AP, Nelson KA. Terahertz-Driven Stark Spectroscopy of CdSe and CdSe-CdS Core-Shell Quantum Dots. Nano Lett 2019; 19:8125-8131. [PMID: 31635457 DOI: 10.1021/acs.nanolett.9b03342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The effects of large external fields on semiconductor nanostructures could reveal much about field-induced shifting of electronic states and their dynamical responses and could enable electro-optic device applications that require large and rapid changes in optical properties. Studies of quasi-dc electric field modulation of quantum dot (QD) properties have been limited by electrostatic breakdown processes observed under high externally applied field levels. To circumvent this, here we apply ultrafast terahertz (THz) electric fields with switching times on the order of 1 ps. We show that a pulsed THz electric field, enhanced by a microslit field enhancement structure (FES), can strongly manipulate the optical absorption properties of a thin film of CdSe and CdSe-CdS core-shell QDs on the subpicosecond time scale with spectral shifts that span the visible to near-IR range. Numerical simulations using a semiempirical tight binding model show that the band gap of the QD film can be shifted by as much a 79 meV during these time scales. The results allow a basic understanding of the field-induced shifting of electronic levels and suggest electro-optic device applications.
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Affiliation(s)
- Brandt C Pein
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - Chee Kong Lee
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - Liang Shi
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - JiaoJian Shi
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - Wendi Chang
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - Harold Y Hwang
- Lincoln Laboratory , Massachusetts Institute of Technology , Lexington , Massachusetts 02420 United States
| | - Jennifer Scherer
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - Igor Coropceanu
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - Xiaoguang Zhao
- Department of Mechanical Engineering , Boston University , Boston , Massachusetts 02215 United States
| | - Xin Zhang
- Department of Mechanical Engineering , Boston University , Boston , Massachusetts 02215 United States
| | - Vladimir Bulović
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - Moungi G Bawendi
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - Adam P Willard
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - Keith A Nelson
- Department of Chemistry and Department of Electrical Engineering and Computer Science , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
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34
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Wu Y, Ringe S, Wu CL, Chen W, Yang A, Chen H, Tang M, Zhou G, Hwang HY, Chan K, Cui Y. A Two-Dimensional MoS 2 Catalysis Transistor by Solid-State Ion Gating Manipulation and Adjustment (SIGMA). Nano Lett 2019; 19:7293-7300. [PMID: 31499003 DOI: 10.1021/acs.nanolett.9b02888] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A variety of methods including tuning chemical compositions, structures, crystallinity, defects and strain, and electrochemical intercalation have been demonstrated to enhance the catalytic activity. However, none of these tuning methods provide direct dynamical control during catalytic reactions. Here we propose a new method to tune the activity of catalysts through solid-state ion gating manipulation and adjustment (SIGMA) using a catalysis transistor. SIGMA can electrostatically dope the surface of catalysts with a high electron concentration over 5 × 1013 cm-2 and thus modulate both the chemical potential of the reaction intermediates and their electrical conductivity. The hydrogen evolution reaction (HER) on both pristine and defective MoS2 were investigated as model reactions. Our theoretical and experimental results show that the overpotential at 10 mA/cm2 and Tafel slope can be in situ, continuously, dynamically, and reversibly tuned over 100 mV and around 100 mV/dec, respectively.
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Affiliation(s)
- Yecun Wu
- Department of Electrical Engineering , Stanford University , Stanford , California 94305 , United States
| | - Stefan Ringe
- SUNCAT Center for Interface Science and Catalysis , Stanford University , Stanford , California 94305 , United States
- SUNCAT Center for Interface Science and Catalysis , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
| | - Chun-Lan Wu
- Department of Materials Science and Engineering , Stanford University , Stanford , California 94305 , United States
| | - Wei Chen
- Department of Materials Science and Engineering , Stanford University , Stanford , California 94305 , United States
| | - Ankun Yang
- Department of Materials Science and Engineering , Stanford University , Stanford , California 94305 , United States
| | - Hao Chen
- Department of Materials Science and Engineering , Stanford University , Stanford , California 94305 , United States
| | - Michael Tang
- SUNCAT Center for Interface Science and Catalysis , Stanford University , Stanford , California 94305 , United States
- SUNCAT Center for Interface Science and Catalysis , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
| | - Guangmin Zhou
- Department of Materials Science and Engineering , Stanford University , Stanford , California 94305 , United States
| | - Harold Y Hwang
- Department of Applied Physics , Stanford University , Stanford , California 94305 , United States
- Stanford Institute for Materials and Energy Science , SLAC National Accelerator Laboratory , Menlo Park , California 94025 United States
| | - Karen Chan
- CatTheory Center, Department of Physics , Technical University of Denmark , Kongens Lyngby 2800 , Denmark
| | - Yi Cui
- Department of Materials Science and Engineering , Stanford University , Stanford , California 94305 , United States
- Stanford Institute for Materials and Energy Science , SLAC National Accelerator Laboratory , Menlo Park , California 94025 United States
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35
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Abstract
Crystalline oxide ferroelectric tunnel junctions enable persistent encoding of information in electric polarization, featuring nondestructive readout and scalability that can exceed current commercial high-speed, nonvolatile ferroelectric memories. However, the well-established fabrication of epitaxial devices on oxide substrates is difficult to adapt to silicon substrates for integration into complementary metal-oxide-semiconductor electronics. In this work, we report ferroelectric tunnel junctions based on 2.8 nm-thick BaTiO3 films grown epitaxially on SrTiO3 growth substrates, released, and relaminated onto silicon. The performance of the transferred devices is comparable to devices characterized on the oxide substrate, suggesting a viable route toward next-generation nonvolatile memories broadly integrable with different materials platforms.
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Affiliation(s)
- Di Lu
- Department of Physics , Stanford University , Stanford , California 94305 , United States
| | - Sam Crossley
- Department of Applied Physics , Stanford University , Stanford , California 94305 , United States
| | - Ruijuan Xu
- Department of Applied Physics , Stanford University , Stanford , California 94305 , United States
- Stanford Institute for Materials and Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
| | - Harold Y Hwang
- Department of Applied Physics , Stanford University , Stanford , California 94305 , United States
- Stanford Institute for Materials and Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
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36
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Lee K, Osada M, Hwang HY, Hikita Y. Oxygen Evolution Reaction Activity in IrO x/SrIrO 3 Catalysts: Correlations between Structural Parameters and the Catalytic Activity. J Phys Chem Lett 2019; 10:1516-1522. [PMID: 30883127 DOI: 10.1021/acs.jpclett.9b00173] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Understanding how structural properties affect the oxygen evolution reaction (OER) of a catalyst can reveal important information not only on the catalytic mechanism but also on the general design strategy of OER catalysts. We report a variation of ∼0.15 V in the overpotential of the recently discovered IrO x/SrIrO3 OER catalysts, which directly correlates with the structural parameters of the as-synthesized SrIrO3 epitaxial films. This variation is caused by both extrinsic area enhancement and intrinsic electronic structure modification driven by defect formation. These correlations not only indicate that microscopic film defects play an important role in the activity of the IrO x/SrIrO3 catalyst but also provide readily accessible parameters predictive of the activity post-transformation to IrO x/SrIrO3. Establishing strong associations between the catalytic activity and key structural and electronic parameters, rather than synthetic variables, provides important guidance to control and study these complex catalysts independent of the synthetic technique.
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Affiliation(s)
- Kyuho Lee
- Department of Physics , Stanford University , Stanford , California 94305 , United States
- Geballe Laboratory for Advanced Materials, Department of Applied Physics , Stanford University , Stanford , California 94305 , United States
| | - Motoki Osada
- Geballe Laboratory for Advanced Materials, Department of Applied Physics , Stanford University , Stanford , California 94305 , United States
- Materials Science & Engineering , Stanford University , Stanford , California 94305 , United States
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Department of Applied Physics , Stanford University , Stanford , California 94305 , United States
- Stanford Institute for Materials & Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
| | - Yasuyuki Hikita
- Stanford Institute for Materials & Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
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37
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Chen Z, Swartz AG, Yoon H, Inoue H, Merz TA, Lu D, Xie Y, Yuan H, Hikita Y, Raghu S, Hwang HY. Publisher Correction: Carrier density and disorder tuned superconductor-metal transition in a two-dimensional electron system. Nat Commun 2018; 9:4570. [PMID: 30374115 PMCID: PMC6206007 DOI: 10.1038/s41467-018-06960-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA. .,Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA. .,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
| | - Adrian G Swartz
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.,Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Hyeok Yoon
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.,Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Hisashi Inoue
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.,Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Tyler A Merz
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.,Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Di Lu
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.,Department of Physics, Stanford University, Stanford, CA, 94305, USA
| | - Yanwu Xie
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.,Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Hongtao Yuan
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Yasuyuki Hikita
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Srinivas Raghu
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.,Department of Physics, Stanford University, Stanford, CA, 94305, USA
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA. .,Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA. .,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
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38
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Swartz AG, Cheung AKC, Yoon H, Chen Z, Hikita Y, Raghu S, Hwang HY. Superconducting Tunneling Spectroscopy of Spin-Orbit Coupling and Orbital Depairing in Nb:SrTiO_{3}. Phys Rev Lett 2018; 121:167003. [PMID: 30387624 DOI: 10.1103/physrevlett.121.167003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Indexed: 06/08/2023]
Abstract
We have examined the intrinsic spin-orbit coupling and orbital depairing in thin films of Nb-doped SrTiO_{3} by superconducting tunneling spectroscopy. The orbital depairing is geometrically suppressed in the two-dimensional limit, enabling a quantitative evaluation of the Fermi level spin-orbit scattering using Maki's theory. The response of the superconducting gap under in-plane magnetic fields demonstrates short spin-orbit scattering times τ_{so}≤1.1 ps. Analysis of the orbital depairing indicates that the heavy electron band contributes significantly to pairing. These results suggest that the intrinsic spin-orbit scattering time in SrTiO_{3} is comparable to those associated with Rashba effects in SrTiO_{3} interfacial conducting layers and can be considered significant in all forms of superconductivity in SrTiO_{3}.
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Affiliation(s)
- Adrian G Swartz
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Alfred K C Cheung
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Hyeok Yoon
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Srinivas Raghu
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
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39
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Hristov AT, Palmstrom JC, Straquadine JAW, Merz TA, Hwang HY, Fisher IR. Measurement of elastoresistivity at finite frequency by amplitude demodulation. Rev Sci Instrum 2018; 89:103901. [PMID: 30399873 DOI: 10.1063/1.5031136] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 08/09/2018] [Indexed: 06/08/2023]
Abstract
Elastoresistivity, the relation between resistivity and strain, can elucidate the subtle properties of the electronic structure of a material and is an increasingly important tool for the study of strongly correlated materials. To date, elastoresistivity measurements have predominantly been performed with quasi-static (DC) strain. In this work, we demonstrate a method using AC strain in elastoresistivity measurements. A sample experiencing AC strain has a time-dependent resistivity, which modulates the voltage produced by an AC current; this effect produces time-dependent variations in resistivity that are directly proportional to the elastoresistivity, and which can be measured more quickly, with less strain on the sample, and with less stringent requirements for temperature stability than the previous DC technique. Example measurements between 10 Hz and 3 kHz are performed on a material with a large, well-characterized and temperature dependent elastoresistivity: the representative iron-based superconductor Ba(Fe0.975Co0.025)2As2. These measurements yield a frequency independent elastoresistivity and reproduce results from previous DC elastoresistivity methods to within experimental accuracy. We emphasize that the dynamic (AC) elastoresistivity is a distinct material-specific property that has not previously been considered.
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Affiliation(s)
- Alexander T Hristov
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Johanna C Palmstrom
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Joshua A W Straquadine
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Tyler A Merz
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Ian R Fisher
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
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40
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Chen Z, Swartz AG, Yoon H, Inoue H, Merz TA, Lu D, Xie Y, Yuan H, Hikita Y, Raghu S, Hwang HY. Carrier density and disorder tuned superconductor-metal transition in a two-dimensional electron system. Nat Commun 2018; 9:4008. [PMID: 30275443 PMCID: PMC6167361 DOI: 10.1038/s41467-018-06444-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 09/02/2018] [Indexed: 11/08/2022] Open
Abstract
Quantum ground states that arise at atomically controlled oxide interfaces provide an opportunity to address key questions in condensed matter physics, including the nature of two-dimensional metallic behaviour often observed adjacent to superconductivity. At the superconducting LaAlO3/SrTiO3 interface, a metallic ground state emerges upon the collapse of superconductivity with field-effect gating and is accompanied with a pseudogap. Here we utilize independent control of carrier density and disorder of the interfacial superconductor using dual electrostatic gates, which enables the comprehensive examination of the electronic phase diagram approaching zero temperature. We find that the pseudogap corresponds to precursor pairing, and the onset of long-range phase coherence forms a two-dimensional superconducting dome as a function of the dual-gate voltages. The gate-tuned superconductor-metal transitions are driven by macroscopic phase fluctuations of Josephson coupled superconducting puddles.
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Affiliation(s)
- Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
| | - Adrian G Swartz
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Hyeok Yoon
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Hisashi Inoue
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Tyler A Merz
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Di Lu
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
| | - Yanwu Xie
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Hongtao Yuan
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Yasuyuki Hikita
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Srinivas Raghu
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
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41
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Emori S, Yi D, Crossley S, Wisser JJ, Balakrishnan PP, Khodadadi B, Shafer P, Klewe C, N'Diaye AT, Urwin BT, Mahalingam K, Howe BM, Hwang HY, Arenholz E, Suzuki Y. Ultralow Damping in Nanometer-Thick Epitaxial Spinel Ferrite Thin Films. Nano Lett 2018; 18:4273-4278. [PMID: 29792812 DOI: 10.1021/acs.nanolett.8b01261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Pure spin currents, unaccompanied by dissipative charge flow, are essential for realizing energy-efficient nanomagnetic information and communications devices. Thin-film magnetic insulators have been identified as promising materials for spin-current technology because they are thought to exhibit lower damping compared with their metallic counterparts. However, insulating behavior is not a sufficient requirement for low damping, as evidenced by the very limited options for low-damping insulators. Here, we demonstrate a new class of nanometer-thick ultralow-damping insulating thin films based on design criteria that minimize orbital angular momentum and structural disorder. Specifically, we show ultralow damping in <20 nm thick spinel-structure magnesium aluminum ferrite (MAFO), in which magnetization arises from Fe3+ ions with zero orbital angular momentum. These epitaxial MAFO thin films exhibit a Gilbert damping parameter of ∼0.0015 and negligible inhomogeneous linewidth broadening, resulting in narrow half width at half-maximum linewidths of ∼0.6 mT around 10 GHz. Our findings offer an attractive thin-film platform for enabling integrated insulating spintronics.
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Affiliation(s)
- Satoru Emori
- Department of Physics , Virginia Polytechnic Institute and State University , Blacksburg , Virginia 24060 , United States
| | | | | | | | | | - Behrouz Khodadadi
- Department of Physics , Virginia Polytechnic Institute and State University , Blacksburg , Virginia 24060 , United States
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Christoph Klewe
- Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Alpha T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Brittany T Urwin
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | - Krishnamurthy Mahalingam
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | - Brandon M Howe
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | | | - Elke Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
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Abstract
Electric-double-layer (EDL) gating with liquid electrolyte has been a powerful tool widely used to explore emerging interfacial electronic phenomena. Due to the large EDL capacitance, a high carrier density up to 1014 cm-2 can be induced, directly leading to the realization of field-induced insulator to metal (or superconductor) transition. However, the liquid nature of the electrolyte has created technical issues including possible side electrochemical reactions or intercalation, and the potential for huge strain at the interface during cooling. In addition, the liquid coverage of active devices also makes many surface characterizations and in situ measurements challenging. Here, we demonstrate an all solid-state EDL device based on a solid superionic conductor LaF3, which can be used as both a substrate and a fluorine ionic gate dielectric to achieve a wide tunability of carrier density without the issues of strain or electrochemical reactions and can expose the active device surface for external access. Based on LaF3 EDL transistors (EDLTs), we observe the metal-insulator transition in MoS2. Interestingly, the well-defined crystal lattice provides a more uniform potential distribution in the substrate, resulting in less interface electron scattering and therefore a higher mobility in MoS2 transistors. This result shows the powerful gating capability of LaF3 solid electrolyte for new possibilities of novel interfacial electronic phenomena.
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Affiliation(s)
- Chun-Lan Wu
- Department of Material Science and Engineering , Stanford University , Stanford , California 94305 , United States
| | - Hongtao Yuan
- Department of Material Science and Engineering , Stanford University , Stanford , California 94305 , United States
- Stanford Institute for Materials and Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
- National Laboratory of Solid-State Microstructures, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Yanbin Li
- Department of Material Science and Engineering , Stanford University , Stanford , California 94305 , United States
| | - Yongji Gong
- Department of Material Science and Engineering , Stanford University , Stanford , California 94305 , United States
- School of Material Science and Engineering , Beihang University , Beijing 100191 , China
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
- Department of Applied Physics , Stanford University , Stanford , California 94305 , United States
| | - Yi Cui
- Department of Material Science and Engineering , Stanford University , Stanford , California 94305 , United States
- Stanford Institute for Materials and Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
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43
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Zeng J, Liu E, Fu Y, Chen Z, Pan C, Wang C, Wang M, Wang Y, Xu K, Cai S, Yan X, Wang Y, Liu X, Wang P, Liang SJ, Cui Y, Hwang HY, Yuan H, Miao F. Gate-Induced Interfacial Superconductivity in 1T-SnSe 2. Nano Lett 2018; 18:1410-1415. [PMID: 29385803 DOI: 10.1021/acs.nanolett.7b05157] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Layered metal chalcogenide materials provide a versatile platform to investigate emergent phenomena and two-dimensional (2D) superconductivity at/near the atomically thin limit. In particular, gate-induced interfacial superconductivity realized by the use of an electric-double-layer transistor (EDLT) has greatly extended the capability to electrically induce superconductivity in oxides, nitrides, and transition metal chalcogenides and enable one to explore new physics, such as the Ising pairing mechanism. Exploiting gate-induced superconductivity in various materials can provide us with additional platforms to understand emergent interfacial superconductivity. Here, we report the discovery of gate-induced 2D superconductivity in layered 1T-SnSe2, a typical member of the main-group metal dichalcogenide (MDC) family, using an EDLT gating geometry. A superconducting transition temperature Tc ≈ 3.9 K was demonstrated at the EDL interface. The 2D nature of the superconductivity therein was further confirmed based on (1) a 2D Tinkham description of the angle-dependent upper critical field Bc2, (2) the existence of a quantum creep state as well as a large ratio of the coherence length to the thickness of superconductivity. Interestingly, the in-plane Bc2 approaching zero temperature was found to be 2-3 times higher than the Pauli limit, which might be related to an electric field-modulated spin-orbit interaction. Such results provide a new perspective to expand the material matrix available for gate-induced 2D superconductivity and the fundamental understanding of interfacial superconductivity.
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Affiliation(s)
- Junwen Zeng
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Erfu Liu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Yajun Fu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
- School of Material Science and Engineering, Southwest University of Science and Technology , Mianyang 621010, China
| | - Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Chen Pan
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Chenyu Wang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Miao Wang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Yaojia Wang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Kang Xu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Songhua Cai
- College of Engineering and Applied Sciences, Nanjing University , Nanjing 210093, China
| | - Xingxu Yan
- College of Engineering and Applied Sciences, Nanjing University , Nanjing 210093, China
| | - Yu Wang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Xiaowei Liu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Peng Wang
- College of Engineering and Applied Sciences, Nanjing University , Nanjing 210093, China
| | - Shi-Jun Liang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Yi Cui
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Hongtao Yuan
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Feng Miao
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
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Lu J, Li X, Zhang Y, Hwang HY, Ofori-Okai BK, Nelson KA. Two-Dimensional Spectroscopy at Terahertz Frequencies. Top Curr Chem (Cham) 2018; 376:6. [DOI: 10.1007/s41061-018-0185-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 01/05/2018] [Indexed: 10/18/2022]
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Frenkel Y, Haham N, Shperber Y, Bell C, Xie Y, Chen Z, Hikita Y, Hwang HY, Salje EKH, Kalisky B. Imaging and tuning polarity at SrTiO 3 domain walls. Nat Mater 2017; 16:1203-1208. [PMID: 28920939 DOI: 10.1038/nmat4966] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 07/13/2017] [Indexed: 06/07/2023]
Abstract
Electrostatic fields tune the ground state of interfaces between complex oxide materials. Electronic properties, such as conductivity and superconductivity, can be tuned and then used to create and control circuit elements and gate-defined devices. Here we show that naturally occurring twin boundaries, with properties that are different from their surrounding bulk, can tune the LaAlO3/SrTiO3 interface 2DEG at the nanoscale. In particular, SrTiO3 domain boundaries have the unusual distinction of remaining highly mobile down to low temperatures, and were recently suggested to be polar. Here we apply localized pressure to an individual SrTiO3 twin boundary and detect a change in LaAlO3/SrTiO3 interface current distribution. Our data directly confirm the existence of polarity at the twin boundaries, and demonstrate that they can serve as effective tunable gates. As the location of SrTiO3 domain walls can be controlled using external field stimuli, our findings suggest a novel approach to manipulate SrTiO3-based devices on the nanoscale.
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Affiliation(s)
- Yiftach Frenkel
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Noam Haham
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Yishai Shperber
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Christopher Bell
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - Yanwu Xie
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Physics, Zhejiang University, Hangzhou 310027, China
- Department of Applied Physics, Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford University, Stanford, California 94305, USA
| | - Zhuoyu Chen
- Department of Applied Physics, Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford University, Stanford, California 94305, USA
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford University, Stanford, California 94305, USA
| | - Ekhard K H Salje
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
| | - Beena Kalisky
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
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46
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Hong SS, Yu JH, Lu D, Marshall AF, Hikita Y, Cui Y, Hwang HY. Two-dimensional limit of crystalline order in perovskite membrane films. Sci Adv 2017; 3:eaao5173. [PMID: 29167822 PMCID: PMC5696264 DOI: 10.1126/sciadv.aao5173] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 10/19/2017] [Indexed: 05/11/2023]
Abstract
Long-range order and phase transitions in two-dimensional (2D) systems-such as magnetism, superconductivity, and crystallinity-have been important research topics for decades. The issue of 2D crystalline order has reemerged recently, with the development of exfoliated atomic crystals. Understanding the dimensional limit of crystalline phases, with different types of bonding and synthetic techniques, is at the foundation of low-dimensional materials design. We study ultrathin membranes of SrTiO3, an archetypal perovskite oxide with isotropic (3D) bonding. Atomically controlled membranes are released after synthesis by dissolving an underlying epitaxial layer. Although all unreleased films are initially single-crystalline, the SrTiO3 membrane lattice collapses below a critical thickness (5 unit cells). This crossover from algebraic to exponential decay of the crystalline coherence length is analogous to the 2D topological Berezinskii-Kosterlitz-Thouless (BKT) transition. The transition is likely driven by chemical bond breaking at the 2D layer-3D bulk interface, defining an effective dimensional phase boundary for coherent crystalline lattices.
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Affiliation(s)
- Seung Sae Hong
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Corresponding author. (S.S.H.); (H.Y.H.)
| | - Jung Ho Yu
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA
| | - Di Lu
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | | | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Yi Cui
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Harold Y. Hwang
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Corresponding author. (S.S.H.); (H.Y.H.)
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47
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Pein BC, Chang W, Hwang HY, Scherer J, Coropceanu I, Zhao X, Zhang X, Bulović V, Bawendi M, Nelson KA. Terahertz-Driven Luminescence and Colossal Stark Effect in CdSe-CdS Colloidal Quantum Dots. Nano Lett 2017; 17:5375-5380. [PMID: 28786683 DOI: 10.1021/acs.nanolett.7b01837] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Optical properties of colloidal semiconductor quantum dots (QDs), arising from quantum mechanical confinement of charge, present a versatile testbed for the study of how high electric fields affect the electronic structure of nanostructured solids. Studies of quasi-DC electric field modulation of QD properties have been limited by electrostatic breakdown processes under high externally applied electric fields, which have restricted the range of modulation of QD properties. In contrast, here we drive CdSe-CdS core-shell QD films with high-field THz-frequency electromagnetic pulses whose duration is only a few picoseconds. Surprisingly, in response to the THz excitation, we observe QD luminescence even in the absence of an external charge source. Our experiments show that QD luminescence is associated with a remarkably high and rapid modulation of the QD bandgap, which changes by more than 0.5 eV (corresponding to 25% of the unperturbed bandgap energy). We show that these colossal energy shifts can be explained by the quantum confined Stark effect even though we are far outside the regime of small field-induced shifts in electronic energy levels. Our results demonstrate a route to extreme modulation of material properties and to a compact, high-bandwidth THz detector that operates at room temperature.
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Affiliation(s)
- Brandt C Pein
- Department of Chemistry and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Wendi Chang
- Department of Chemistry and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Harold Y Hwang
- Massachusetts Institute of Technology Lincoln Laboratory , Lexington, Massachusetts 02420, United States
| | - Jennifer Scherer
- Department of Chemistry and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Igor Coropceanu
- Department of Chemistry and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Xiaoguang Zhao
- Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215, United States
| | - Xin Zhang
- Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215, United States
| | - Vladimir Bulović
- Department of Chemistry and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Moungi Bawendi
- Department of Chemistry and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Keith A Nelson
- Department of Chemistry and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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48
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Liu X, Kang JH, Yuan H, Park J, Kim SJ, Cui Y, Hwang HY, Brongersma ML. Electrical tuning of a quantum plasmonic resonance. Nat Nanotechnol 2017; 12:866-870. [PMID: 28604706 DOI: 10.1038/nnano.2017.103] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 04/25/2017] [Indexed: 06/07/2023]
Abstract
Surface plasmon (SP) excitations in metals facilitate confinement of light into deep-subwavelength volumes and can induce strong light-matter interaction. Generally, the SP resonances supported by noble metal nanostructures are explained well by classical models, at least until the nanostructure size is decreased to a few nanometres, approaching the Fermi wavelength λF of the electrons. Although there is a long history of reports on quantum size effects in the plasmonic response of nanometre-sized metal particles, systematic experimental studies have been hindered by inhomogeneous broadening in ensemble measurements, as well as imperfect control over size, shape, faceting, surface reconstructions, contamination, charging effects and surface roughness in single-particle measurements. In particular, observation of the quantum size effect in metallic films and its tuning with thickness has been challenging as they only confine carriers in one direction. Here, we show active tuning of quantum size effects in SP resonances supported by a 20-nm-thick metallic film of indium tin oxide (ITO), a plasmonic material serving as a low-carrier-density Drude metal. An ionic liquid (IL) is used to electrically gate and partially deplete the ITO layer. The experiment shows a controllable and reversible blue-shift in the SP resonance above a critical voltage. A quantum-mechanical model including the quantum size effect reproduces the experimental results, whereas a classical model only predicts a red shift.
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Affiliation(s)
- Xiaoge Liu
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Ju-Hyung Kang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Hongtao Yuan
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- National Laboratory of Solid-State Microstructures, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Junghyun Park
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Soo Jin Kim
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Yi Cui
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Mark L Brongersma
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
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49
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Wu J, Yuan H, Meng M, Chen C, Sun Y, Chen Z, Dang W, Tan C, Liu Y, Yin J, Zhou Y, Huang S, Xu HQ, Cui Y, Hwang HY, Liu Z, Chen Y, Yan B, Peng H. High electron mobility and quantum oscillations in non-encapsulated ultrathin semiconducting Bi 2O 2Se. Nat Nanotechnol 2017; 12:530-534. [PMID: 28369044 DOI: 10.1038/nnano.2017.43] [Citation(s) in RCA: 195] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 02/20/2017] [Indexed: 05/07/2023]
Abstract
High-mobility semiconducting ultrathin films form the basis of modern electronics, and may lead to the scalable fabrication of highly performing devices. Because the ultrathin limit cannot be reached for traditional semiconductors, identifying new two-dimensional materials with both high carrier mobility and a large electronic bandgap is a pivotal goal of fundamental research. However, air-stable ultrathin semiconducting materials with superior performances remain elusive at present. Here, we report ultrathin films of non-encapsulated layered Bi2O2Se, grown by chemical vapour deposition, which demonstrate excellent air stability and high-mobility semiconducting behaviour. We observe bandgap values of ∼0.8 eV, which are strongly dependent on the film thickness due to quantum-confinement effects. An ultrahigh Hall mobility value of >20,000 cm2 V-1 s-1 is measured in as-grown Bi2O2Se nanoflakes at low temperatures. This value is comparable to what is observed in graphene grown by chemical vapour deposition and at the LaAlO3-SrTiO3 interface, making the detection of Shubnikov-de Haas quantum oscillations possible. Top-gated field-effect transistors based on Bi2O2Se crystals down to the bilayer limit exhibit high Hall mobility values (up to 450 cm2 V-1 s-1), large current on/off ratios (>106) and near-ideal subthreshold swing values (∼65 mV dec-1) at room temperature. Our results make Bi2O2Se a promising candidate for future high-speed and low-power electronic applications.
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Affiliation(s)
- Jinxiong Wu
- Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Hongtao Yuan
- National Laboratory of Solid-State Microstructures, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Mengmeng Meng
- Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Cheng Chen
- Department of Physics and Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Yan Sun
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China
| | - Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Wenhui Dang
- Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Congwei Tan
- Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Yujing Liu
- Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Jianbo Yin
- Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Yubing Zhou
- Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Shaoyun Huang
- Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - H Q Xu
- Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Yi Cui
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Zhongfan Liu
- Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Yulin Chen
- Department of Physics and Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Binghai Yan
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China
| | - Hailin Peng
- Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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50
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Lu J, Li X, Hwang HY, Ofori-Okai BK, Kurihara T, Suemoto T, Nelson KA. Coherent Two-Dimensional Terahertz Magnetic Resonance Spectroscopy of Collective Spin Waves. Phys Rev Lett 2017; 118:207204. [PMID: 28581810 DOI: 10.1103/physrevlett.118.207204] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Indexed: 05/27/2023]
Abstract
We report a demonstration of two-dimensional (2D) terahertz (THz) magnetic resonance spectroscopy using the magnetic fields of two time-delayed THz pulses. We apply the methodology to directly reveal the nonlinear responses of collective spin waves (magnons) in a canted antiferromagnetic crystal. The 2D THz spectra show all of the third-order nonlinear magnon signals including magnon spin echoes, and 2-quantum signals that reveal pairwise correlations between magnons at the Brillouin zone center. We also observe second-order nonlinear magnon signals showing resonance-enhanced second-harmonic and difference-frequency generation. Numerical simulations of the spin dynamics reproduce all of the spectral features in excellent agreement with the experimental 2D THz spectra.
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Affiliation(s)
- Jian Lu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Xian Li
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Harold Y Hwang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Benjamin K Ofori-Okai
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Takayuki Kurihara
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Tohru Suemoto
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Keith A Nelson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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