51
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Qin M, Han X, Ding D, Niu R, Qu Z, Wang Z, Liao ZM, Gan Z, Huang Y, Han C, Lu J, Ye J. Light Controllable Electronic Phase Transition in Ionic Liquid Gated Monolayer Transition Metal Dichalcogenides. NANO LETTERS 2021; 21:6800-6806. [PMID: 34369798 DOI: 10.1021/acs.nanolett.1c01467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Ionic liquid gating has proved to be effective in inducing emergent quantum phenomena such as superconductivity, ferromagnetism, and topological states. The electrostatic doping at two-dimensional interfaces relies on ionic motion, which thus is operated at sufficiently high temperature. Here, we report the in situ tuning of quantum phases by shining light on an ionic liquid-gated interface at cryogenic temperatures. The light illumination enables flexible switching of the quantum transition in monolayer WS2 from an insulator to a superconductor. In contrast to the prevailing picture of photoinduced carriers, we find that in the presence of a strong interfacial electric field conducting electrons could escape from the surface confinement by absorbing photons, mimicking the field emission. Such an optical tuning tool in conjunction with ionic liquid gating greatly facilitates continuous modulation of carrier densities and hence electronic phases, which would help to unveil novel quantum phenomena and device functionality in various materials.
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Affiliation(s)
- Maosen Qin
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Xiangyan Han
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Dongdong Ding
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Ruirui Niu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhuangzhuang Qu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhiyu Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhi-Min Liao
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Yangtze Delta Institute of Optoelectronics, Peking University, Nantong, Jiangsu 226010 China
| | - Zizhao Gan
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Yuan Huang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190 China
| | - Chunrui Han
- Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Jianming Lu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Jianting Ye
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen 9746AG, The Netherlands
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52
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Zhang BY, Xu K, Yao Q, Jannat A, Ren G, Field MR, Wen X, Zhou C, Zavabeti A, Ou JZ. Hexagonal metal oxide monolayers derived from the metal-gas interface. NATURE MATERIALS 2021; 20:1073-1078. [PMID: 33462466 DOI: 10.1038/s41563-020-00899-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 12/03/2020] [Indexed: 05/27/2023]
Abstract
Two-dimensional (2D) crystals are promising materials for developing future nano-enabled technologies1-6. The cleavage of weak, interlayer van der Waals bonds in layered bulk crystals enables the production of high-quality 2D, atomically thin monolayers7-10. Nonetheless, as earth-abundant compounds, metal oxides are rarely accessible as pure and fully stoichiometric monolayers owing to their ion-stabilized 'lamellar' bulk structure11-14. Here, we report the discovery of a layered planar hexagonal phase of oxides from elements across the transition metals, post-transition metals, lanthanides and metalloids, derived from strictly controlled oxidation at the metal-gas interface. The highly crystalline monolayers, without the support of ionic dopants or vacancies, can easily be mechanically exfoliated by stamping them onto substrates. Monolayer and few-layered hexagonal TiO2 are characterized as examples, showing p-type semiconducting properties with hole mobilities of up to 950 cm2 V-1 s-1 at room temperature. The strategy can be readily extended to a variety of elements, possibly expanding the exploration of metal oxides in the 2D quantum regime.
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Affiliation(s)
- Bao Yue Zhang
- School of Engineering, RMIT University, Melbourne, Victoria, Australia
| | - Kai Xu
- School of Engineering, RMIT University, Melbourne, Victoria, Australia
| | - Qifeng Yao
- Beijing Academy of Quantum Information Sciences, Beijing, China
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, China
| | - Azmira Jannat
- School of Engineering, RMIT University, Melbourne, Victoria, Australia
| | - Guanghui Ren
- School of Engineering, RMIT University, Melbourne, Victoria, Australia
- Integrated Photonics and Applications Centre (InPAC), RMIT University, Melbourne, Victoria, Australia
| | - Matthew R Field
- RMIT Microscopy & Microanalysis Facility, RMIT University, Melbourne, Victoria, Australia
| | - Xiaoming Wen
- Centre for Translational Atomaterials, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - Chunhua Zhou
- Centre for Translational Atomaterials, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - Ali Zavabeti
- Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, Australia.
- School of Science, RMIT University, Melbourne, Victoria, Australia.
| | - Jian Zhen Ou
- School of Engineering, RMIT University, Melbourne, Victoria, Australia.
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, China.
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53
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Zhao M, Li J, Sebek M, Yang L, Liu YJ, Bosman M, Wang Q, Zheng X, Lu J, Teng J. Electrostatically Tunable Near-Infrared Plasmonic Resonances in Solution-Processed Atomically Thin NbSe 2. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101950. [PMID: 34176177 DOI: 10.1002/adma.202101950] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/08/2021] [Indexed: 06/13/2023]
Abstract
In the broad spectral range, near-infrared (NIR) plasmonics find applications in telecommunication, energy harvesting, sensing, and more, all of which would benefit from an electrostatically controllable NIR plasmon source. However, it is difficult to control bulk NIR plasmonics directly with electrostatics because of the strong electric-field screening effect and high carrier concentration required to support NIR plasmons. Here, this constraint is overcome and the observation of NIR plasmonic resonances that can be modulated electrostatically over a range of ≈360 cm-1 in few-layer NbSe2 gratings is reported, thanks to the enhanced electrostatics of atomically thin 2D materials and the high-quality film produced by a solution method. NbSe2 plasmons also render strong field confinement due to their atomic thickness and provide an extra degree of resonance frequency modulation from the layered structure. This study identifies metallic 2D materials as promising (easily produced and well-performing) candidates to extend electrostatically tunable plasmonics to the technologically important NIR range.
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Affiliation(s)
- Meng Zhao
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Innovis, Singapore, 138634, Singapore
| | - Jing Li
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Matej Sebek
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Innovis, Singapore, 138634, Singapore
| | - Le Yang
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Innovis, Singapore, 138634, Singapore
| | - Yan Jun Liu
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Michel Bosman
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Innovis, Singapore, 138634, Singapore
- Department of Material Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Qian Wang
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Innovis, Singapore, 138634, Singapore
| | - Xinting Zheng
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Innovis, Singapore, 138634, Singapore
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Jinghua Teng
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Innovis, Singapore, 138634, Singapore
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54
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Venditti G, Maccari I, Grilli M, Caprara S. Finite-Frequency Dissipation in Two-Dimensional Superconductors with Disorder at the Nanoscale. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:1888. [PMID: 34443718 PMCID: PMC8401199 DOI: 10.3390/nano11081888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 07/07/2021] [Accepted: 07/20/2021] [Indexed: 11/17/2022]
Abstract
Two-dimensional superconductors with disorder at the nanoscale can host a variety of intriguing phenomena. The superconducting transition is marked by a broad percolative transition with a long tail of the resistivity as function of the temperature. The fragile filamentary superconducting clusters, forming at low temperature, can be strengthened further by proximity effect with the surrounding metallic background, leading to an enhancement of the superfluid stiffness well below the percolative transition. Finite-frequency dissipation effects, e.g., related to the appearance of thermally excited vortices, can also significantly contribute to the resulting physics. Here, we propose a random impedance model to investigate the role of dissipation effects in the formation and strengthening of fragile superconducting clusters, discussing the solution within the effective medium theory.
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Affiliation(s)
| | | | | | - Sergio Caprara
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro, 5, I-00185 Roma, Italy; (G.V.); (I.M.); (M.G.)
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55
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Lin T, Wang X, Chen X, Liu X, Luo X, Li X, Jing X, Dong Q, Liu B, Liu H, Li Q, Zhu X, Liu B. Retainable Superconductivity and Structural Transition in 1T-TaSe 2 Under High Pressure. Inorg Chem 2021; 60:11385-11393. [PMID: 34289304 DOI: 10.1021/acs.inorgchem.1c01378] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
As a prominent platform possessing the properties of superconductivity (SC) and charge density wave (CDW), transition-metal dichalcogenides (TMDCs) have attracted considerable attention for a long time. Moreover, extensive efforts have been devoted for exploring the SC and/or the interplay between SC and CDW in TMDCs in the past few decades. Here, we systematically investigate the electronic properties and structural evolution of 1T-TaSe2 under pressure. With increasing pressure, pressure-induced superconductivity is observed at ∼2.6 GPa. The superconductive transition temperature (Tc) increases with the suppression of the CDW state to the maximum value of ∼5.1 K at 21.8 GPa and then decreases monotonously up to the highest pressure of 57.8 GPa. 1T-TaSe2 transforms into a monoclinic C2/m structure above 19 GPa. The monoclinic phase coexists with the original phase as the pressure is released under ambient conditions and the retainable superconductivity with Tc = 2.9 K is observed in the released sample. We suggest that the retained superconductivity can be ascribed to the retention of the superconductive high-pressure monoclinic phase in the released sample. Our findings demonstrate that both the structure and CDW order are related to the superconductivity of TaSe2.
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Affiliation(s)
- Tao Lin
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Xiaojun Wang
- Laboratory of High Pressure Physics and Material Science, School of Physics and Physical Engineering, Qufu Normal University, Qufu 273100, People's Republic of China
| | - Xin Chen
- Laboratory of High Pressure Physics and Material Science, School of Physics and Physical Engineering, Qufu Normal University, Qufu 273100, People's Republic of China
| | - Xiaobing Liu
- Laboratory of High Pressure Physics and Material Science, School of Physics and Physical Engineering, Qufu Normal University, Qufu 273100, People's Republic of China
| | - Xuan Luo
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Xue Li
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Xiaoling Jing
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Qing Dong
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Bo Liu
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Hanyu Liu
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Quanjun Li
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Xuebin Zhu
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Bingbing Liu
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China
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56
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Walmsley TS, Xu YQ. Enhanced photocurrent response speed in charge-density-wave phase of TiSe 2-metal junctions. NANOSCALE 2021; 13:11836-11843. [PMID: 34160523 DOI: 10.1039/d1nr01810h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Group IVB transition metal dichalcogenides (TMDCs) have attracted significant attention due to their predicted high charge carrier mobility, large sheet current density, and enhanced thermoelectric power. Here, we investigate the electrical and optoelectronic properties of few-layer titanium diselenide (TiSe2)-metal junctions through spatial-, wavelength-, temperature-, power- and temporal-dependent scanning photocurrent measurements. Strong photocurrent responses have been detected at TiSe2-metal junctions, which is likely attributed to both photovoltaic and photothermoelectric effects. A fast response time of 31 μs has been achieved, which is two orders of magnitude better than HfSe2 based devices. More importantly, our experimental results reveal a significant enhancement in the response speed upon cooling to the charge-density-wave (CDW) phase transition temperature (TCDW = 206 K), which may result from dramatic reduction in carrier scattering that occurs as a result of the switching between the normal and CDW phases of TiSe2. Additionally, the photoresponsivity at 145 K is up to an order of magnitude higher than that obtained at room temperature. These fundamental studies not only offer insight for the photocurrent generation mechanisms of group IVB TMDC materials, but also provide a route to engineering future temperature-dependent, two-dimensional, fast electronic and optoelectronic devices.
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Affiliation(s)
- Thayer S Walmsley
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA.
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57
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Duan S, Cheng Y, Xia W, Yang Y, Xu C, Qi F, Huang C, Tang T, Guo Y, Luo W, Qian D, Xiang D, Zhang J, Zhang W. Optical manipulation of electronic dimensionality in a quantum material. Nature 2021; 595:239-244. [PMID: 34234338 DOI: 10.1038/s41586-021-03643-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 05/13/2021] [Indexed: 02/06/2023]
Abstract
Exotic phenomena can be achieved in quantum materials by confining electronic states into two dimensions. For example, relativistic fermions are realized in a single layer of carbon atoms1, the quantized Hall effect can result from two-dimensional (2D) systems2,3, and the superconducting transition temperature can be considerably increased in a one-atomic-layer material4,5. Ordinarily, a 2D electronic system can be obtained by exfoliating the layered materials, growing monolayer materials on substrates, or establishing interfaces between different materials. Here we use femtosecond infrared laser pulses to invert the periodic lattice distortion sectionally in a three-dimensional (3D) charge density wave material (1T-TiSe2), creating macroscopic domain walls of transient 2D ordered electronic states with unusual properties. The corresponding ultrafast electronic and lattice dynamics are captured by time-resolved and angle-resolved photoemission spectroscopy6 and ultrafast electron diffraction at energies of the order of megaelectronvolts7. Moreover, in the photoinduced 2D domain wall near the surface we identify a phase with enhanced density of states and signatures of potential opening of an energy gap near the Fermi energy. Such optical modulation of atomic motion is an alternative path towards realizing 2D electronic states and will be a useful platform upon which novel phases in quantum materials may be discovered.
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Affiliation(s)
- Shaofeng Duan
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Yun Cheng
- Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Wei Xia
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yuanyuan Yang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Chengyang Xu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Fengfeng Qi
- Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Chaozhi Huang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Tianwei Tang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Yanfeng Guo
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
| | - Weidong Luo
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.,Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai, China
| | - Dong Qian
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.,Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China
| | - Dao Xiang
- Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China. .,Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China. .,Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai, China.
| | - Jie Zhang
- Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Wentao Zhang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.
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58
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Aamir MA, Moore JN, Lu X, Seifert P, Englund D, Fong KC, Efetov DK. Ultrasensitive Calorimetric Measurements of the Electronic Heat Capacity of Graphene. NANO LETTERS 2021; 21:5330-5337. [PMID: 34101476 DOI: 10.1021/acs.nanolett.1c01553] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Heat capacity is an invaluable quantity in condensed matter physics and yet has been completely inaccessible in two-dimensional (2D) van der Waals (vdW) materials, owing to their ultrafast thermal relaxation times and the lack of suitable nanoscale thermometers. Here, we demonstrate a novel thermal relaxation calorimetry scheme that allows the first measurements of the electronic heat capacity of graphene. It is enabled by combining a radio frequency Johnson noise thermometer, which can measure the electronic temperature with a sensitivity of ∼20 mK/Hz1/2, and a photomixed optical heater that modulates Te with a frequency of up to Ω = 0.2 THz. This allows record sensitive measurements of the electronic heat capacity Ce < 10 -19 J/K and the fastest measurement of electronic thermal relaxation time τe < 10 -12 s yet achieved by a calorimeter. These features advance heat capacity metrology into the realm of nanoscale and low-dimensional systems and provide an avenue for the investigation of their thermodynamic quantities.
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Affiliation(s)
- Mohammed Ali Aamir
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
| | - John N Moore
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
| | - Xiaobo Lu
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
| | - Paul Seifert
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
| | - Dirk Englund
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kin Chung Fong
- Quantum Information Processing Group, Raytheon BBN Technologies, Cambridge, Massachusetts 02138, United States
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Dmitri K Efetov
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
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59
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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] [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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60
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Abstract
Abstract
Ionic gating is a very popular tool to investigate and control the electric charge transport and electronic ground state in a wide variety of different materials. This is due to its capability to induce large modulations of the surface charge density by means of the electric-double-layer field-effect transistor (EDL-FET) architecture, and has been proven to be capable of tuning even the properties of metallic systems. In this short review, I summarize the main results which have been achieved so far in controlling the superconducting (SC) properties of thin films of conventional metallic superconductors by means of the ionic gating technique. I discuss how the gate-induced charge doping, despite being confined to a thin surface layer by electrostatic screening, results in a long-range ‘bulk’ modulation of the SC properties by the coherent nature of the SC condensate, as evidenced by the observation of suppressions in the critical temperature of films much thicker than the electrostatic screening length, and by the pronounced thickness-dependence of their magnitude. I review how this behavior can be modelled in terms of proximity effect between the charge-doped surface layer and the unperturbed bulk with different degrees of approximation, and how first-principles calculations have been employed to determine the origin of an anomalous increase in the electrostatic screening length at ultrahigh electric fields, thus fully confirming the validity of the proximity effect model. Finally, I discuss a general framework—based on the combination of ab-initio Density Functional Theory and the Migdal-Eliashberg theory of superconductivity—by which the properties of any gated thin film of a conventional metallic superconductor can be determined purely from first principles.
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61
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Lee JM, Oshikawa M, Cho GY. Non-Fermi Liquids in Conducting Two-Dimensional Networks. PHYSICAL REVIEW LETTERS 2021; 126:186601. [PMID: 34018806 DOI: 10.1103/physrevlett.126.186601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 04/01/2021] [Indexed: 06/12/2023]
Abstract
We explore the physics of novel fermion liquids emerging from conducting networks, where 1D metallic wires form a periodic 2D superstructure. Such structure naturally appears in marginally twisted bilayer graphenes, moire transition metal dichalcogenides, and also in some charge-density wave materials. For these network systems, we theoretically show that a remarkably wide variety of new non-Fermi liquids emerge and that these non-Fermi liquids can be classified by the characteristics of the junctions in networks. Using this, we calculate the electric conductivity of the non-Fermi liquids as a function of temperature, which show markedly different scaling behaviors than a regular 2D Fermi liquid.
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Affiliation(s)
- Jongjun M Lee
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Masaki Oshikawa
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
- Kavli Institute for the Physics and Mathematics of the Universe, Kashiwa 277-8583, Japan
- Trans-scale Quantum Science Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Gil Young Cho
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
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62
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Qiu D, Gong C, Wang S, Zhang M, Yang C, Wang X, Xiong J. Recent Advances in 2D Superconductors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2006124. [PMID: 33768653 DOI: 10.1002/adma.202006124] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/22/2020] [Indexed: 06/12/2023]
Abstract
The emergence of superconductivity in 2D materials has attracted much attention and there has been rapid development in recent years because of their fruitful physical properties, such as high transition temperature (Tc ), continuous phase transition, and enhanced parallel critical magnetic field (Bc ). Tremendous efforts have been devoted to exploring different physical parameters to figure out the mechanisms behind the unexpected superconductivity phenomena, including adjusting the thickness of samples, fabricating various heterostructures, tuning the carrier density by electric field and chemical doping, and so on. Here, different types of 2D superconductivity with their unique characteristics are introduced, including the conventional Bardeen-Cooper-Schrieffer superconductivity in ultrathin films, high-Tc superconductivity in Fe-based and Cu-based 2D superconductors, unconventional superconductivity in newly discovered twist-angle bilayer graphene, superconductivity with enhanced Bc , and topological superconductivity. A perspective toward this field is then proposed based on academic knowledge from the recently reported literature. The aim is to provide researchers with a clear and comprehensive understanding about the newly developed 2D superconductivity and promote the development of this field much further.
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Affiliation(s)
- Dong Qiu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Chuanhui Gong
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - SiShuang Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Miao Zhang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Chao Yang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Xianfu Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Jie Xiong
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
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63
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Campi D, Kumari S, Marzari N. Prediction of Phonon-Mediated Superconductivity with High Critical Temperature in the Two-Dimensional Topological Semimetal W 2N 3. NANO LETTERS 2021; 21:3435-3442. [PMID: 33856216 DOI: 10.1021/acs.nanolett.0c05125] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Two-dimensional superconductors attract great interest both for their fundamental physics and for their potential applications, especially in the rapidly growing field of quantum computing. Despite intense theoretical and experimental efforts, materials with a reasonably high transition temperature are still rare. Even more rare are those that combine superconductivity with a nontrivial band topology that could potentially give rise to exotic states of matter. Here, we predict a remarkably high superconducting critical temperature of 21 K in the easily exfoliable, topologically nontrivial 2D semimetal W2N3. By studying its electronic and superconducting properties as a function of doping and strain, we also find large changes in the electron-phonon interactions that make this material a unique platform to study different coupling regimes and test the limits of current theories of superconductivity. Last, we discuss the possibility of tuning the material to achieve coexistence of superconductivity and topologically nontrivial edge states.
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Affiliation(s)
- Davide Campi
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Simran Kumari
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Nicola Marzari
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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64
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Wang J, Shi Q, Shih EM, Zhou L, Wu W, Bai Y, Rhodes D, Barmak K, Hone J, Dean CR, Zhu XY. Diffusivity Reveals Three Distinct Phases of Interlayer Excitons in MoSe_{2}/WSe_{2} Heterobilayers. PHYSICAL REVIEW LETTERS 2021; 126:106804. [PMID: 33784140 DOI: 10.1103/physrevlett.126.106804] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 09/13/2020] [Accepted: 01/25/2021] [Indexed: 06/12/2023]
Abstract
Charge separated interlayer excitons in transition metal dichalcogenide heterobilayers are being explored for moiré exciton lattices and exciton condensates. The presence of permanent dipole moments and the poorly screened Coulomb interaction make many-body interactions particularly strong for interlayer excitons. Here we reveal two distinct phase transitions for interlayer excitons in the MoSe_{2}/WSe_{2} heterobilayer using time and spatially resolved photoluminescence imaging: from trapped excitons in the moiré potential to the modestly mobile exciton gas as exciton density increases to n_{ex}∼10^{11} cm^{-2} and from the exciton gas to the highly mobile charge separated electron-hole plasma for n_{ex}>10^{12} cm^{-2}. The latter is the Mott transition and is confirmed in photoconductivity measurements. These findings set fundamental limits for achieving quantum states of interlayer excitons.
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Affiliation(s)
- Jue Wang
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Qianhui Shi
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - En-Min Shih
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - Lin Zhou
- Department of Chemistry, Columbia University, New York, New York 10027, USA
- College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, People's Republic of China
| | - Wenjing Wu
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Yusong Bai
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Daniel Rhodes
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA
| | - Katayun Barmak
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA
| | - Cory R Dean
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - X-Y Zhu
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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65
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King PDC, Picozzi S, Egdell RG, Panaccione G. Angle, Spin, and Depth Resolved Photoelectron Spectroscopy on Quantum Materials. Chem Rev 2021; 121:2816-2856. [PMID: 33346644 DOI: 10.1021/acs.chemrev.0c00616] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of X-ray based electron spectroscopies in determining chemical, electronic, and magnetic properties of solids has been well-known for several decades. A powerful approach is angle-resolved photoelectron spectroscopy, whereby the kinetic energy and angle of photoelectrons emitted from a sample surface are measured. This provides a direct measurement of the electronic band structure of crystalline solids. Moreover, it yields powerful insights into the electronic interactions at play within a material and into the control of spin, charge, and orbital degrees of freedom, central pillars of future solid state science. With strong recent focus on research of lower-dimensional materials and modified electronic behavior at surfaces and interfaces, angle-resolved photoelectron spectroscopy has become a core technique in the study of quantum materials. In this review, we provide an introduction to the technique. Through examples from several topical materials systems, including topological insulators, transition metal dichalcogenides, and transition metal oxides, we highlight the types of information which can be obtained. We show how the combination of angle, spin, time, and depth-resolved experiments are able to reveal "hidden" spectral features, connected to semiconducting, metallic and magnetic properties of solids, as well as underlining the importance of dimensional effects in quantum materials.
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Affiliation(s)
- Phil D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Silvia Picozzi
- Consiglio Nazionale delle Ricerche, CNR-SPIN, Via dei Vestini 31, Chieti 66100, Italy
| | - Russell G Egdell
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Giancarlo Panaccione
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
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66
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Li Z, Wu Q, Wu C. Surface/Interface Chemistry Engineering of Correlated-Electron Materials: From Conducting Solids, Phase Transitions to External-Field Response. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2002807. [PMID: 33643796 PMCID: PMC7887576 DOI: 10.1002/advs.202002807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 09/25/2020] [Indexed: 06/12/2023]
Abstract
Correlated electronic materials (CEMs) with strong electron-electron interactions are often associated with exotic properties, such as metal-insulator transition (MIT), charge density wave (CDW), superconductivity, and magnetoresistance (MR), which are fundamental to next generation condensed matter research and electronic devices. When the dimension of CEMs decreases, exposing extremely high specific surface area and enhancing electronic correlation, the surface states are equally important to the bulk phase. Therefore, surface/interface chemical interactions provide an alternative route to regulate the intrinsic properties of low-dimensional CEMs. Here, recent achievements in surface/interface chemistry engineering of low-dimensional CEMs are reviewed, using surface modification, molecule-solid interaction, and interface electronic coupling, toward modulation of conducting solids, phase transitions including MIT, CDW, superconductivity, and magnetism transition, as well as external-field response. Surface/interface chemistry engineering provides a promising strategy for exploring novel properties and functional applications in low-dimensional CEMs. Finally, the current challenge and outlook of the surface/interface engineering are also pointed out for future research development.
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Affiliation(s)
- Zejun Li
- Hefei National Laboratory for Physical Sciences at the MicroscaleCAS center for Excellence in Nanoscienceand CAS Key Laboratory of Mechanical Behavior and Design of MaterialsUniversity of Science and Technology of ChinaHefeiAnhui230026PR China
| | - Qiran Wu
- Hefei National Laboratory for Physical Sciences at the MicroscaleCAS center for Excellence in Nanoscienceand CAS Key Laboratory of Mechanical Behavior and Design of MaterialsUniversity of Science and Technology of ChinaHefeiAnhui230026PR China
| | - Changzheng Wu
- Hefei National Laboratory for Physical Sciences at the MicroscaleCAS center for Excellence in Nanoscienceand CAS Key Laboratory of Mechanical Behavior and Design of MaterialsUniversity of Science and Technology of ChinaHefeiAnhui230026PR China
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67
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Yang W, Mo CJ, Fu SB, Yang Y, Zheng FW, Wang XH, Liu YA, Hao N, Zhang P. Soft-Mode-Phonon-Mediated Unconventional Superconductivity in Monolayer 1T^{'}-WTe_{2}. PHYSICAL REVIEW LETTERS 2020; 125:237006. [PMID: 33337229 DOI: 10.1103/physrevlett.125.237006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 10/30/2020] [Accepted: 10/30/2020] [Indexed: 06/12/2023]
Abstract
Recent experiments have tuned the monolayer 1T^{'}-WTe_{2} to be superconducting by electrostatic gating. Here, we theoretically study the phonon-mediated superconductivity in monolayer 1T^{'}-WTe_{2} via charge doping. We reveal that the emergence of soft-mode phonons with specific momentum is crucial to give rise to the superconductivity in the electron-doping regime, whereas no such soft-mode phonons and no superconductivity emerge in the hole-doping regime. We also find a superconducting dome, which can be attributed to the change of Fermi surface nesting conditions with electron doping. By taking into account the experimentally established strong anisotropy of temperature-dependent upper critical field H_{c2} between the in-plane and out-of-plane directions, we show that the superconducting state probably has the unconventional equal-spin-triplet pairing in the A_{u} channel of the C_{2h} point group. Our studies provide a promising understanding to the doping dependent superconductivity and strong anisotropy of H_{c2} in monolayer 1T^{'}-WTe_{2}, and can be extended to understand the superconductivity in other gated transition metal dichalcogenides.
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Affiliation(s)
- Wei Yang
- Beijing Key Laboratory of Work Safety Intelligent Monitoring, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Chong-Jie Mo
- Beijing Computational Science Research Center, Beijing 100193, China
| | - Shi-Bin Fu
- Beijing Key Laboratory of Work Safety Intelligent Monitoring, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Yu Yang
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
| | - Fa-Wei Zheng
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
| | - Xiao-Hui Wang
- Beijing Key Laboratory of Work Safety Intelligent Monitoring, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Yuan-An Liu
- Beijing Key Laboratory of Work Safety Intelligent Monitoring, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Ning Hao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Ping Zhang
- Beijing Computational Science Research Center, Beijing 100193, China
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China
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68
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de Ory MC, Rollano V, Gomez A, Menghini M, Muñoz-Noval A, Gonzalez EM, Vicent JL. Little–Parks effect governed by magnetic nanostructures with out-of-plane magnetization. Sci Rep 2020; 10:10370. [PMID: 32587400 PMCID: PMC7316768 DOI: 10.1038/s41598-020-67317-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 06/05/2020] [Indexed: 11/09/2022] Open
Abstract
AbstractLittle–Parks effect names the oscillations in the superconducting critical temperature as a function of the magnetic field. This effect is related to the geometry of the sample. In this work, we show that this effect can be enhanced and manipulated by the inclusion of magnetic nanostructures with perpendicular magnetization. These magnetic nanodots generate stray fields with enough strength to produce superconducting vortex–antivortex pairs. So that, the L–P effect deviation from the usual geometrical constrictions is due to the interplay between local magnetic stray fields and superconducting vortices. Moreover, we compare our results with a low-stray field sample (i.e. with the dots in magnetic vortex state) showing how the enhancement of the L–P effect can be explained by an increment of the effective size of the nanodots.
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69
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Huang Y, Wolowiec C, Zhu T, Hu Y, An L, Li Z, Grossman JC, Schuller IK, Ren S. Emerging Magnetic Interactions in van der Waals Heterostructures. NANO LETTERS 2020; 20:7852-7859. [PMID: 33054240 DOI: 10.1021/acs.nanolett.0c02175] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Vertical van der Waals (vdWs) heterostructures based on layered materials are attracting interest as a new class of quantum materials, where interfacial charge-transfer coupling can give rise to fascinating strongly correlated phenomena. Transition metal chalcogenides are a particularly exciting material family, including ferromagnetic semiconductors, multiferroics, and superconductors. Here, we report the growth of an organic-inorganic heterostructure by intercalating molecular electron donating bis(ethylenedithio)tetrathiafulvalene into (Li,Fe)OHFeSe, a layered material in which the superconducting ground state results from the intercalation of hydroxide layer. Molecular intercalation in this heterostructure induces a transformation from a paramagnetic to spin-glass-like state that is sensitive to the stoichiometry of molecular donor and an applied magnetic field. Besides, electron-donating molecules reduce the electrical resistivity in the heterostructure and modify its response to laser illumination. This hybrid heterostructure provides a promising platform to study emerging magnetic and electronic behaviors in strongly correlated layered materials.
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Affiliation(s)
- Yulong Huang
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Christian Wolowiec
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, California 92093, United States
| | - Taishan Zhu
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yong Hu
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Lu An
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Zheng Li
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Jeffrey C Grossman
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ivan K Schuller
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, California 92093, United States
| | - Shenqiang Ren
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
- Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
- Research and Education in Energy, Environment, and Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
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70
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Zhang S, Li C, Shang J, Li H, Wang Z, Li L, Jia Y. Magnetism arising from Mexican-hat-like band dispersion in the WSe 2/SnS 2 heterostructure via interlayer strain. Phys Chem Chem Phys 2020; 22:21961-21967. [PMID: 32974632 DOI: 10.1039/d0cp03141k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mexican-hat-like band dispersion is extremely critical to the realization of hole-doping-induced magnetism in monolayer metal monochalcogenides. However, it is absent from transition-metal dichalcogenides (TMDCs), i.e., WSe2. Herein, using first-principles calculations, we show that Mexican-hat-like band dispersion can be achieved by applying interlayer strain (ε) in the WSe2/SnS2 van der Waals (vdW) heterostructure when ε exceeds 15%. This is because in the strain-induced distorted trigonal prismatic crystal field, at the valence band edge, the W_dz2 orbitals shift upward around the Γ point, while the double-degenerate W_dxy/dx2-y2 orbitals shift downward at the K point, resulting in Mexican-hat-like band dispersion near the Γ point when the energy level of the Γ point surpasses that of the K point. On account of the appearance of the Mexican-hat-like band edge (MHBE), hole-doping in the strained WSe2/SnS2 heterostructure induces magnetization readily from the nonmagnetized phase. Our findings may provide a new strategy for the realization of magnetized TMDC-based vdW heterostructures.
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Affiliation(s)
- Shuai Zhang
- School of Physics and Engineering, Henan University of Science and Technology, Luoyang 471023, China.
| | - Chong Li
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China.
| | - Jimin Shang
- School of Physics and Electronics Engineering, Zhengzhou University of Light Industry, Zhengzhou 453002, China
| | - Haisheng Li
- School of Physics and Engineering, Henan University of Science and Technology, Luoyang 471023, China.
| | - Zhaowu Wang
- School of Physics and Engineering, Henan University of Science and Technology, Luoyang 471023, China.
| | - Liben Li
- School of Physics and Engineering, Henan University of Science and Technology, Luoyang 471023, China.
| | - Yu Jia
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China.
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71
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Li Z, Xia W, Su H, Yu Z, Fu Y, Chen L, Wang X, Yu N, Zou Z, Guo Y. Magnetic critical behavior of the van der Waals Fe 5GeTe 2 crystal with near room temperature ferromagnetism. Sci Rep 2020; 10:15345. [PMID: 32948794 PMCID: PMC7501290 DOI: 10.1038/s41598-020-72203-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 08/27/2020] [Indexed: 12/03/2022] Open
Abstract
The van der Waals ferromagnet Fe5GeTe2 has a Curie temperature TC of about 270 K, which is tunable through controlling the Fe deficiency content and can even reach above room temperature. To achieve insights into its ferromagnetic exchange that gives the high TC, the critical behavior has been investigated by measuring the magnetization in Fe5GeTe2 crystal around the ferromagnetic ordering temperature. The analysis of the measured magnetization by using various techniques harmonically reached to a set of reliable critical exponents with TC = 273.7 K, β = 0.3457 ± 0.001, γ = 1.40617 ± 0.003, and δ = 5.021 ± 0.001. By comparing these critical exponents with those predicted by various models, it seems that the magnetic properties of Fe5GeTe2 could be interpreted by a three-dimensional magnetic exchange with the exchange distance decaying as J(r) ≈ r−4.916, close to that of a three-dimensional Heisenberg model with long-range magnetic coupling.
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Affiliation(s)
- Zhengxian Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wei Xia
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hao Su
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhenhai Yu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yunpeng Fu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Leiming Chen
- School of Materials Science and Engineering, Henan Key Laboratory of Aeronautic Materials and Application Technology, Zhengzhou University of Aeronautics, Zhengzhou, 450046, Henan, China.
| | - Xia Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,Analytical Instrumentation Center, School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Na Yu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,Analytical Instrumentation Center, School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Zhiqiang Zou
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,Analytical Instrumentation Center, School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yanfeng Guo
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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72
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Miller AM, Hamann DM, Hadland EC, Johnson DC. Investigating the Formation of MoSe 2 and TiSe 2 Films from Artificially Layered Precursors. Inorg Chem 2020; 59:12536-12544. [PMID: 32805989 DOI: 10.1021/acs.inorgchem.0c01626] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reaction of ultrathin layers of Mo and Ti with Se was investigated, and significantly different reaction pathways were found. However, in both systems postdeposition annealing results in smooth dichalcogenide films with specific thicknesses determined by the precursor. X-ray diffraction (XRD) patterns of as-deposited Mo|Se films around a 1:2 ratio of Mo to Se contain weak, broad reflections from small and isolated MoSe2 crystallites that nucleated during deposition and a sharper intensity maximum resulting from the composition modulation created from the alternating deposition of Mo and Se layers. In contrast, as-deposited Ti|Se films around a 1:2 ratio of Ti to Se contain narrow and intense 00l reflections from TiSe2 crystallites and do not contain a Bragg reflection from the sequence of deposited Ti|Se layers. The as-deposited TiSe2 crystallites have a larger c-axis lattice parameter than was previously reported for TiSe2, however, which suggests a poor vertical interlayer registry and/or high defect densities including interstitial atoms. In-plane XRD patterns show the nucleation of both TiSe2 and Ti2Se during deposition, with the Ti2Se at the substrate. For both systems, annealing the precursors decreases the peak width and increases the intensity of reflections from crystalline TiSe2 and MoSe2. Optimized films consist of a single phase after the annealing and show clear Laue oscillations in the specular XRD patterns, which can only occur if a majority of the diffracting crystallites in the film consist of the same number of unit cells. The highest quality films was obtained when an excess of ∼10% Se was deposited in the precursor, which presumably acts as a flux to facilitate diffusion of metal atoms to crystallite growth fronts and compensates for Se loss to the open system during annealing.
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Affiliation(s)
- Aaron M Miller
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, United States
| | - Danielle M Hamann
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, United States
| | - Erik C Hadland
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, United States
| | - David C Johnson
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, United States
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73
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Hsu YT, Cole WS, Zhang RX, Sau JD. Inversion-Protected Higher-Order Topological Superconductivity in Monolayer WTe_{2}. PHYSICAL REVIEW LETTERS 2020; 125:097001. [PMID: 32915630 DOI: 10.1103/physrevlett.125.097001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Accepted: 08/06/2020] [Indexed: 06/11/2023]
Abstract
Monolayer WTe_{2}, a centrosymmetric transition metal dichacogenide, has recently been established as a quantum spin Hall insulator and found superconducting upon gating. Here we study the pairing symmetry and topological nature of superconducting WTe_{2} with a microscopic model at mean-field level. Surprisingly, we find that the spin-triplet phases in our phase diagram all host Majorana modes localized on two opposite corners. Even when the conventional pairing is favored, we find that an intermediate in-plane magnetic field exceeding the Pauli limit stabilizes an unconventional equal-spin pairing aligning with the field, which also hosts Majorana corner modes. Motivated by our findings, we obtain a recipe for two-dimensional superconductors featuring "higher-order topology" from the boundary perspective. Generally, a superconducting inversion-symmetric quantum spin Hall material whose normal-state Fermi surface is away from high-symmetry points, such as gated monolayer WTe_{2}, hosts Majorana corner modes if the superconductivity is parity-odd. We further point out that this higher-order phase is an inversion-protected topological crystalline superconductor and study the bulk-boundary correspondence. Finally, we discuss possible experiments for probing the Majorana corner modes. Our findings suggest superconducting monolayer WTe_{2} is a playground for higher-order topological superconductivity and possibly the first material realization for inversion-protected Majorana corner modes without utilizing proximity effect.
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Affiliation(s)
- Yi-Ting Hsu
- Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - William S Cole
- Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Rui-Xing Zhang
- Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Jay D Sau
- Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
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Bekaert J, Sevik C, Milošević MV. First-principles exploration of superconductivity in MXenes. NANOSCALE 2020; 12:17354-17361. [PMID: 32789416 DOI: 10.1039/d0nr03875j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
MXenes are an emerging class of two-dimensional materials, which in their thinnest limit consist of a monolayer of carbon or nitrogen (X) sandwiched between two transition metal (M) layers. We have systematically searched for superconductivity among MXenes for a range of transition metal elements, based on a full first-principles characterization in combination with the Eliashberg formalism. Thus, we identified six superconducting MXenes: three carbides (Mo2C, W2C and Sc2C) and three nitrides (Mo2N, W2N and Ta2N). The highest critical temperature of ∼16 K is found in Mo2N, for which a successful synthesis method has been established [Urbankowski et al., Nanoscale, 2017, 9, 17722-17730]. Moreover, W2N presents a novel case of competing superconducting and charge density wave phases.
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Affiliation(s)
- Jonas Bekaert
- Department of Physics & NANOlab Center of Excellence, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
| | - Cem Sevik
- Department of Mechanical Engineering, Faculty of Engineering, Eskisehir Technical University, 26555 Eskisehir, Turkey
| | - Milorad V Milošević
- Department of Physics & NANOlab Center of Excellence, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
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75
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Latt KZ, Schlueter JA, Darancet P, Hla SW. Two-Dimensional Molecular Charge Density Waves in Single-Layer-Thick Islands of a Dirac Fermion System. ACS NANO 2020; 14:8887-8893. [PMID: 32574034 DOI: 10.1021/acsnano.0c03694] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Charge density waves have been intensely studied in inorganic materials such as transition metal dichalcogenides; however their counterpart in organic materials has yet to be explored in detail. Here we report the finding of robust two-dimensional charge density waves in molecular layers formed by α-(BEDT-TTF)2-I3 on a Ag(111) surface. Low-temperature scanning tunneling microscopy images of a multilayer thick α-(BEDT-TTF)2-I3 on a Ag(111) substrate reveal the coexistence of 5a0 × 5a0 and 31a0×31a0 R9° charge density wave patterns commensurate with the underlying molecular lattice at 80 K. Both charge density wave patterns remain in nanosize molecular islands with just a single constituent molecular-layer thickness at 80 and 5 K. Local tunneling spectroscopy measurements reveal the variation of the gap from 244 to 288 meV between the maximum and minimum charge density wave locations. Density functional theory calculations further confirm a vertical positioning of BEDT-TTF molecules in the molecular layer. While the observed charge density wave patterns are stable for the defect sites, they can be reversibly switched for one molecular lattice site by means of inelastic tunneling electron energy transfer with the electron energies exceeding 400 meV using a scanning tunneling microscope manipulation scheme.
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Affiliation(s)
- Kyaw Zin Latt
- Nanoscale and Quantum Phenomena Institute, Physics & Astronomy Department, Ohio University, Athens, Ohio 45701, United States
| | - John A Schlueter
- Division of Materials Research, National Science Foundation, Alexandria, Virginia 22314, United States
| | - Pierre Darancet
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States
| | - Saw-Wai Hla
- Nanoscale and Quantum Phenomena Institute, Physics & Astronomy Department, Ohio University, Athens, Ohio 45701, United States
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States
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76
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Hu Q, Xu S, Guo X, Liu H, Chen Z, Wang B, Ang R. Superconductivity related to the suppression of exciton formation in 1T-TiSe 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:425602. [PMID: 32720648 DOI: 10.1088/1361-648x/aba1ab] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 07/01/2020] [Indexed: 06/11/2023]
Abstract
In strongly correlated electron system, the impact of elementary substitution or intercalation plays a crucial role in determining electronic ground state among various macroscopic quantum phases such as charge order and superconductivity. Here, we report that simultaneous Cu intercalation and Ta substitution at Ti site in 1T-CuxTi0.8Ta0.2Se2induce an intrinsic electronic phase diagram, characterized by an inherent superconducting transition in thexregion of 0 ⩽x⩽ 0.12, with a maximum superconducting transition temperatureTcof 2.5 K forx= 0.04, in contrast to the non-superconducting sample 1T-Cu0.04TiSe2. The increased density of free charge carriers screen the Coulomb interaction between electron-hole pairs effectively, promoting the occurrence of superconductivity favourably. Present results suggest that the Cu intercalation and the Ta substitution-induced suppression of the exciton condensation boost the superconductivity, shedding new light on the fundamental physics of the interplay between superconductivity, charge order, and electron correlation.
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Affiliation(s)
- Qing Hu
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
| | - Shuxiang Xu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Xuming Guo
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
| | - Hangtian Liu
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
| | - Zhiyu Chen
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
| | - Bosen Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Ran Ang
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
- Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065, People's Republic of China
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77
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Zhou JS, Monacelli L, Bianco R, Errea I, Mauri F, Calandra M. Anharmonicity and Doping Melt the Charge Density Wave in Single-Layer TiSe 2. NANO LETTERS 2020; 20:4809-4815. [PMID: 32496779 DOI: 10.1021/acs.nanolett.0c00597] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Low-dimensional systems with a vanishing band gap and a large electron-hole interaction have been proposed to be unstable toward exciton formation. As the exciton binding energy increases in low dimension, conventional wisdom suggests that excitonic insulators should be more stable in 2D than in 3D. Here we study the effects of the electron-hole interaction and anharmonicity in single-layer TiSe2. We find that, contrary to the bulk case and to the generally accepted picture, in single-layer TiSe2, the electron-hole exchange interaction is much smaller in 2D than in 3D and it has weak effects on phonon spectra. By calculating anharmonic phonon spectra within the stochastic self-consistent harmonic approximation, we obtain TCDW ≈ 440 K for an isolated and undoped single layer and TCDW ≈ 364 K for an electron-doping n = 4.6 × 1013 cm-2, close to the experimental result of 200-280 K on supported samples. Our work demonstrates that anharmonicity and doping melt the charge density wave in single-layer TiSe2.
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Affiliation(s)
- Jianqiang Sky Zhou
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - Lorenzo Monacelli
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Raffaello Bianco
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia-San Sebastián, Basque Country, Spain
| | - Ion Errea
- Fisika Aplikatua 1 Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), Europa Plaza 1, 20018 Donostia-San Sebastián, Basque Country, Spain
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia-San Sebastián, Basque Country, Spain
- Donostia International Physics Center (DIPC), Manuel de Lardizabal pasealekua 4, 20018 Donostia-San Sebastián, Basque Country, Spain
| | - Francesco Mauri
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- Graphene Laboratories, Fondazione Istituto Italiano di Tecnologia, Via Morego, I-16163 Genova, Italy
| | - Matteo Calandra
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
- Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo, Italy
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78
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Yin R, Ma L, Wang Z, Ma C, Chen X, Wang B. Reversible Superconductor-Insulator Transition in (Li, Fe)OHFeSe Flakes Visualized by Gate-Tunable Scanning Tunneling Spectroscopy. ACS NANO 2020; 14:7513-7519. [PMID: 32510920 DOI: 10.1021/acsnano.0c03289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Electric field control of charge carrier density provides a key in situ technology to continuously tune the ground states and map out the phase diagram of correlated electron systems in one device. This technique is highly expected to be combined with the modern state-of-the art spectroscopic probes, such as angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy (STM/S), to efficiently address these states and the underlying physics. However, it is extremely difficult and not successful so far, mainly because the fabrication process of such devices makes them prohibitive for surface probes. Here, by using a solid Li-ion conductor (SIC) as gate dielectric, we have successfully developed gate-tunable STM/S and visualized the superconductor-insulator transition (SIT) in a thin flake of single crystal (Li, Fe)OHFeSe at the nanoscale. The gate-controlled Li-ion injection first enhances the superconductivity and then drives the flake into an inhomogeneous insulating state, where superconductivity is totally suppressed. This process can be reversed by applying an opposite gate voltage. Importantly, the atomically resolved images allow us to identify the critical role that the injected Li ions play in the tuning process. Our results not only provide clear evidence of the microscopic mechanism of the tunable superconductivity and SIT in the SIC-based (Li, Fe)OHFeSe devices, but also establish SIC-gating STM as a powerful tool for investigating the complicated phase diagram of correlated electron system spectroscopically in a single sample with the field-effect approach.
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Affiliation(s)
- Ruoting Yin
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Likuan Ma
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Department of Physics, and CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Zhenyu Wang
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Department of Physics, and CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Chuanxu Ma
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Xianhui Chen
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Department of Physics, and CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- CAS Center for Excellence in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China
| | - Bing Wang
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- CAS Center for Excellence in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China
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79
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Liu H, Li G, E D, Xu N, Lin Q, Gao X, Lan C, Chen J, Wang C, Zhan X, Zhang K. Room temperature ferromagnetism in D-D neutron irradiated rutile TiO 2 single crystals. RSC Adv 2020; 10:18687-18693. [PMID: 35518325 PMCID: PMC9053997 DOI: 10.1039/d0ra02220a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 04/20/2020] [Indexed: 11/25/2022] Open
Abstract
Room temperature ferromagnetism (RTFM) was observed in unirradiated rutile TiO2 single crystals prepared by the floating zone method due to oxygen vacancy (VO) defects. D-D neutrons mainly collide elastically with TiO2, producing VO, titanium vacancies (VTi) and other point defects; the density and kind of defect is related to the neutron irradiation fluence. D-D neutron irradiation is used to regulate the concentration and type of defect, avoiding impurity elements. As the irradiation fluence increases, the saturation magnetization (Ms) first increases, then decreases and then increases. To verify the origin of RTFM, the CASTEP module was used to calculate the magnetic and structural properties of point defects in TiO2. VO induces a 2.39 μ B magnetic moment, Ti3+ and F+ induce 1.28 μ B and 1.70 μ B magnetic moments, respectively, while VTi induces a magnetic moment of ∼4 μ B. Combining experimental and theoretical results, increases in VO concentration lead to Ms increases; more VO combine with electrons to form F+, inducing a smaller magnetic moment. VO and VTi play a key role and Ms changes accordingly with larger fluence. VO, F+ and VTi are the most likely origins of RTFM.
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Affiliation(s)
- Huan Liu
- School of Nuclear Science and Technology, Lanzhou University Lanzhou Gansu 730000 China
| | - Gongping Li
- School of Nuclear Science and Technology, Lanzhou University Lanzhou Gansu 730000 China
| | - Dejun E
- School of Nuclear Science and Technology, Lanzhou University Lanzhou Gansu 730000 China
| | - Nannan Xu
- Institute of Modern Physics, Chinese Academy of Sciences Lanzhou Gansu 730000 China
| | - Qiaolu Lin
- School of Nuclear Science and Technology, Lanzhou University Lanzhou Gansu 730000 China
| | - Xudong Gao
- School of Nuclear Science and Technology, Lanzhou University Lanzhou Gansu 730000 China
| | - Changlin Lan
- School of Nuclear Science and Technology, Lanzhou University Lanzhou Gansu 730000 China
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore Singapore 117608 Singapore
| | - Canglong Wang
- Institute of Modern Physics, Chinese Academy of Sciences Lanzhou Gansu 730000 China
| | - Xuwen Zhan
- School of Nuclear Science and Technology, Lanzhou University Lanzhou Gansu 730000 China
| | - Kai Zhang
- China Institute of Atomic Energy Beijing 102413 China
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80
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Vo DD, Idrees M, Pham VT, Vu TV, Nguyen ST, Phuc HV, Hieu NN, Binh NT, Amin B, Nguyen CV. Electronic structure and optical performance of PbI2/SnSe2 heterostructure. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2020.110736] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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81
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Lee JM, Geng C, Park JW, Oshikawa M, Lee SS, Yeom HW, Cho GY. Stable Flatbands, Topology, and Superconductivity of Magic Honeycomb Networks. PHYSICAL REVIEW LETTERS 2020; 124:137002. [PMID: 32302191 DOI: 10.1103/physrevlett.124.137002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 11/08/2019] [Accepted: 03/06/2020] [Indexed: 06/11/2023]
Abstract
We propose a new principle to realize flatbands which are robust in real materials, based on a network superstructure of one-dimensional segments. This mechanism is naturally realized in the nearly commensurate charge-density wave of 1T-TaS_{2} with the honeycomb network of conducting domain walls, and the resulting flatband can naturally explain the enhanced superconductivity. We also show that corner states, which are a hallmark of the higher-order topological insulators, appear in the network superstructure.
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Affiliation(s)
- Jongjun M Lee
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Chenhua Geng
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Jae Whan Park
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Masaki Oshikawa
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Sung-Sik Lee
- Department of Physics & Astronomy, McMaster University, 1280 Main St. W., Hamilton Ontario L85 4M1, Canada
- Perimeter Institute for Theoretical Physics, 31 Caroline ST. N., Waterloo Ontario N2L 2Y5, Canada
| | - Han Woong Yeom
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Gil Young Cho
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
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82
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Spontaneous gyrotropic electronic order in a transition-metal dichalcogenide. Nature 2020; 578:545-549. [DOI: 10.1038/s41586-020-2011-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/05/2019] [Indexed: 11/08/2022]
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83
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Tao Y, Koh SW, Yu X, Wang C, Liang H, Zhang Y, Li H, Wang QJ. Surface group-modified MXene nano-flake doping of monolayer tungsten disulfides. NANOSCALE ADVANCES 2019; 1:4783-4789. [PMID: 36133140 PMCID: PMC9417804 DOI: 10.1039/c9na00395a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 10/07/2019] [Indexed: 05/10/2023]
Abstract
Exciton/trion-involved optoelectronic properties have attracted exponential amount of attention for various applications ranging from optoelectronics, valleytronics to electronics. Herein, we report a new chemical (MXene) doping strategy to modulate the negative trion and neutral exciton for achieving high photoluminescence yield of atomically thin transition metal dichalcogenides, enabled by the regulation of carrier densities to promote electron-bound trion-to-exciton transition via charge transfer from TMDCs to MXene. As a proof of concept, the MXene nano-flake-doped tungsten disulfide is demonstrated to obtain an enhanced PL efficiency of up to ∼five folds, which obviously exceeds the reported efficiency upon electrical and/or plasma doping strategies. The PL enhancement degree can also be modulated by tuning the corresponding surface functional groups of MXene nano-flakes, reflecting that the electron-withdrawing functional groups play a vital role in this charge transfer process. These findings offer promising clues to control the optoelectronic properties of TMDCs and expand the scope of the application of MXene nano-flakes, suggesting a possibility to construct a new heterostructure junction based on MXenes and TMDCs.
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Affiliation(s)
- Ye Tao
- Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, The Photonics Institute, Nanyang Technological University 50 Nanyang Avenue 639798 Singapore
| | - See Wee Koh
- School of Mechanical and Aerospace Engineering, Nanyang Technological University 50 Nanyang Avenue 639798 Singapore
| | - Xuechao Yu
- Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, The Photonics Institute, Nanyang Technological University 50 Nanyang Avenue 639798 Singapore
| | - Chongwu Wang
- Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, The Photonics Institute, Nanyang Technological University 50 Nanyang Avenue 639798 Singapore
| | - Houkun Liang
- Singapore Institute of Manufacturing Technology 71 Nanyang Drive 638075 Singapore
| | - Ying Zhang
- Singapore Institute of Manufacturing Technology 71 Nanyang Drive 638075 Singapore
| | - Hong Li
- School of Mechanical and Aerospace Engineering, Nanyang Technological University 50 Nanyang Avenue 639798 Singapore
| | - Qi Jie Wang
- Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, The Photonics Institute, Nanyang Technological University 50 Nanyang Avenue 639798 Singapore
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84
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Wei R, Tian X, Yang L, Yang D, Ma Z, Guo H, Qiu J. Ultrafast and large optical nonlinearity of a TiSe 2 saturable absorber in the 2 μm wavelength region. NANOSCALE 2019; 11:22277-22285. [PMID: 31570910 DOI: 10.1039/c9nr06374a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The non-equilibrium state of correlated electron materials is crucial for both scientific research and practical applications in optoelectronic and photonic devices. Because of the weak optical nonlinearity of most materials even under a dense optical excitation, it is desirable to achieve a significant nonlinear optical response with ultrafast and large optical nonlinearity utilizing a common material. Here, an ultrafast response and large optical nonlinearity induced by non-equilibrium electrons in typical transition metal dichalcogenides, TiSe2, are investigated in the 1.55-2.0 μm wavelength region. Significantly, we observe an ultrafast transient dynamics of 491 femtoseconds as well as a large optical nonlinearity with a saturable coefficient of -0.17 cm GW-1 (1.55 μm) and -0.10 cm GW-1 (2.0 μm). Upon increasing pump fluence, TiSe2 exhibits an enhanced bleaching response amplitude up to 563%. Furthermore, a stable Q-switched fiber laser in the 2.0 μm wavelength region is achieved by employing the TiSe2-saturable absorber. The findings offer the potential design to enhance the optical nonlinearity via non-equilibrium electrons for advanced photonic devices.
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Affiliation(s)
- Rongfei Wei
- Department of Physics, Zhejiang Normal University, Jinhua, Zhejiang 321004, China.
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85
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Wang D, Luo F, Lu M, Xie X, Huang L, Huang W. Chemical Vapor Transport Reactions for Synthesizing Layered Materials and Their 2D Counterparts. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1804404. [PMID: 31489785 DOI: 10.1002/smll.201804404] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 08/11/2019] [Indexed: 05/12/2023]
Abstract
2D materials, namely thin layers of layered materials, are attracting much attention because of their unique electronic, optical, thermal, and catalytic properties for wide applications. To advance both the fundamental studies and further practical applications, the scalable and controlled synthesis of large-sized 2D materials is desired, while there still lacks ideal approaches. Alternatively, the chemical vapor transport reaction is an old but powerful technique, and is recently adopted for synthesizing 2D materials, producing bulk crystals of layered materials or corresponding 2D films. Herein, recent advancements in synthesizing both bulk layered and 2D materials by chemical vapor transport reactions are summarized. Beginning with a brief introduction of the fundamentals of chemical vapor transport reactions, chemical vapor transport-based syntheses of bulk layered and 2D materials, mainly exampled by transition metal dichalcogenides and black phosphorus, are reviewed. Particular attention is paid to important factors that can influence the reactions and the growth mechanisms of black phosphorus. Finally, perspectives about the chemical vapor transport-based synthesis of 2D materials are discussed, intending to redraw attentions on chemical vapor transport reactions.
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Affiliation(s)
- Dongya Wang
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211816, P. R. China
| | - Fei Luo
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211816, P. R. China
| | - Min Lu
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211816, P. R. China
| | - Xiaoji Xie
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211816, P. R. China
| | - Ling Huang
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211816, P. R. China
| | - Wei Huang
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211816, P. R. China
- Shaanxi Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an, 710072, P. R. China
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86
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Zhang Y, Yao Y, Sendeku MG, Yin L, Zhan X, Wang F, Wang Z, He J. Recent Progress in CVD Growth of 2D Transition Metal Dichalcogenides and Related Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1901694. [PMID: 31402526 DOI: 10.1002/adma.201901694] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/20/2019] [Indexed: 06/10/2023]
Abstract
In recent years, 2D layered materials have received considerable research interest on account of their substantial material systems and unique physicochemical properties. Among them, 2D layered transition metal dichalcogenides (TMDs), a star family member, have already been explored over the last few years and have exhibited excellent performance in electronics, catalysis, and other related fields. However, to fulfill the requirement for practical application, the batch production of 2D TMDs is essential. Recently, the chemical vapor deposition (CVD) technique was considered as an elegant alternative for successfully growing 2D TMDs and their heterostructures. The latest research advances in the controllable synthesis of 2D TMDs and related heterostructures/superlattices via the CVD approach are illustrated here. The controlled growth behavior, preparation strategies, and breakthroughs on the synthesis of new 2D TMDs and their heterostructures, as well as their unique physical phenomena, are also discussed. Recent progress on the application of CVD-grown 2D materials is revealed with particular attention to electronics/optoelectronic devices and catalysts. Finally, the challenges and future prospects are considered regarding the current development of 2D TMDs and related heterostructures.
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Affiliation(s)
- Yu Zhang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Yuyu Yao
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, China
- Sino-Danish College, University of Chinese Academy of Science, Beijing, 100049, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Science, Beijing, 100049, China
| | - Marshet Getaye Sendeku
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Science, Beijing, 100049, China
| | - Lei Yin
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Science, Beijing, 100049, China
| | - Xueying Zhan
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Feng Wang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Zhenxing Wang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Jun He
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, China
- School of Physics and Technology, Wuhan University, Wuhan, 430072, China
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87
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Huan Y, Shi J, Zou X, Gong Y, Xie C, Yang Z, Zhang Z, Gao Y, Shi Y, Li M, Yang P, Jiang S, Hong M, Gu L, Zhang Q, Yan X, Zhang Y. Scalable Production of Two-Dimensional Metallic Transition Metal Dichalcogenide Nanosheet Powders Using NaCl Templates toward Electrocatalytic Applications. J Am Chem Soc 2019; 141:18694-18703. [DOI: 10.1021/jacs.9b06044] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Yahuan Huan
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Jianping Shi
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Xiaolong Zou
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, Guangdong 518055, China
| | - Yue Gong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chunyu Xie
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Zhongjie Yang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Zhepeng Zhang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Yan Gao
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Yuping Shi
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Minghua Li
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Pengfei Yang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Shaolong Jiang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Min Hong
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Qing Zhang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Xiaoqin Yan
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yanfeng Zhang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
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88
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Park JW, Cho GY, Lee J, Yeom HW. Emergent honeycomb network of topological excitations in correlated charge density wave. Nat Commun 2019; 10:4038. [PMID: 31492870 PMCID: PMC6731227 DOI: 10.1038/s41467-019-11981-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Accepted: 08/14/2019] [Indexed: 11/09/2022] Open
Abstract
When two periodic potentials compete in materials, one may adopt the other, which straightforwardly generates topological defects. Of particular interest are domain walls in charge-, dipole-, and spin-ordered systems, which govern macroscopic properties and important functionality. However, detailed atomic and electronic structures of domain walls have often been uncertain and the microscopic mechanism of their functionality has been elusive. Here, we clarify the complete atomic and electronic structures of the domain wall network, a honeycomb network connected by Z3 vortices, in the nearly commensurate Mott charge-density wave (CDW) phase of 1T-TaS2. Scanning tunneling microscopy resolves characteristic charge orders within domain walls and their vortices. Density functional theory calculations disclose their unique atomic relaxations and the metallic in-gap states confined tightly therein. A generic theory is constructed, which connects this emergent honeycomb network of conducting electrons to the enhanced superconductivity.
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Affiliation(s)
- Jae Whan Park
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
| | - Gil Young Cho
- Department of Physics, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Jinwon Lee
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
- Department of Physics, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Han Woong Yeom
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea.
- Department of Physics, Pohang University of Science and Technology, Pohang, 790-784, Korea.
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89
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Wang J, Ardelean J, Bai Y, Steinhoff A, Florian M, Jahnke F, Xu X, Kira M, Hone J, Zhu XY. Optical generation of high carrier densities in 2D semiconductor heterobilayers. SCIENCE ADVANCES 2019; 5:eaax0145. [PMID: 31548986 PMCID: PMC6744266 DOI: 10.1126/sciadv.aax0145] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 08/14/2019] [Indexed: 05/23/2023]
Abstract
Controlling charge density in two-dimensional (2D) materials is a powerful approach for engineering new electronic phases and properties. This control is traditionally realized by electrostatic gating. Here, we report an optical approach for generation of high carrier densities using transition metal dichalcogenide heterobilayers, WSe2/MoSe2, with type II band alignment. By tuning the optical excitation density above the Mott threshold, we realize the phase transition from interlayer excitons to charge-separated electron/hole plasmas, where photoexcited electrons and holes are localized to individual layers. High carrier densities up to 4 × 1014 cm-2 can be sustained under both pulsed and continuous wave excitation conditions. These findings open the door to optical control of electronic phases in 2D heterobilayers.
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Affiliation(s)
- Jue Wang
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Jenny Ardelean
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - Yusong Bai
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Alexander Steinhoff
- Institute for Theoretical Physics, University of Bremen, 28334 Bremen, Germany
| | - Matthias Florian
- Institute for Theoretical Physics, University of Bremen, 28334 Bremen, Germany
| | - Frank Jahnke
- Institute for Theoretical Physics, University of Bremen, 28334 Bremen, Germany
| | - Xiaodong Xu
- Department of Physics and Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, USA
| | - Mackillo Kira
- Department of Electrical Engineering and Computer Science and Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - X.-Y. Zhu
- Department of Chemistry, Columbia University, New York, NY 10027, USA
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90
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Wu HH, Huang H, Zhong J, Yu S, Zhang Q, Zeng XC. Monolayer triphosphates MP 3 (M = Sn, Ge) with excellent basal catalytic activity for hydrogen evolution reaction. NANOSCALE 2019; 11:12210-12219. [PMID: 31204748 DOI: 10.1039/c9nr03255j] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Atomically thin two-dimensional (2D) materials have received intense research interest due to their novel properties and promising applications in nanodevices. By using density functional theory (DFT) calculations, we investigate catalytic activities of several newly predicted two-dimensional (2D) triphosphides GeP3, SnP3 and InP3 monolayers for hydrogen evolution reaction (HER). The calculation results show that GeP3 and SnP3 monolayers are active catalysts for HER with suitable free energy of hydrogen adsorption in the basal plane. In particular, the Gibbs free energy of hydrogen adsorption (ΔGH*) of GeP3 is 0.024 eV, a value even more favorable compared to the precious-group-metal (PGM) catalyst Pt. Moreover, the 2D GeP3 and SnP3 are intrinsically compatible with the graphene substrate so that the HER performance can be improved via building a hybrid multilayer with graphene sheet. The charge transfer from GeP3 or SnP3 to graphene, estimated to be 0.1278e or 0.2157e, can significantly enhance the electric conductivity and promote the electrocatalytic activity. Although the electronic band structure of GeP3 and SnP3 can be tuned by external strain, we find that the HER performance of GeP3 and SnP3 monolayer is actually insensitive to the external strain, a feature desirable for the catalytic application. The desirable properties for HER with nearly zero Gibbs free energy render 2D GeP3 and SnP3 promising candidates for future application in electrocatalysis.
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Affiliation(s)
- Hong-Hui Wu
- Department of Chemistry, University of Nebraska-Lincoln, 8588 Lincoln, NE, USA.
| | - He Huang
- Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jie Zhong
- Department of Chemistry, University of Nebraska-Lincoln, 8588 Lincoln, NE, USA.
| | - Song Yu
- Department of Physics and Materials, East China Normal University, Shanghai 200241, China
| | - Qiaobao Zhang
- Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, Fujian 361005, China.
| | - Xiao Cheng Zeng
- Department of Chemistry, University of Nebraska-Lincoln, 8588 Lincoln, NE, USA.
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91
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Ravnik J, Vaskivskyi I, Gerasimenko Y, Diego M, Vodeb J, Kabanov V, Mihailovic DD. Strain-Induced Metastable Topological Networks in Laser-Fabricated TaS 2 Polytype Heterostructures for Nanoscale Devices. ACS APPLIED NANO MATERIALS 2019; 2:3743-3751. [PMID: 31304463 PMCID: PMC6614884 DOI: 10.1021/acsanm.9b00644] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 05/28/2019] [Indexed: 06/10/2023]
Abstract
The stacking of layered materials into heterostructures offers diverse possibilities for generating deformed moiré states arising from their mutual interaction. Here we report self-assembled two-dimensional nanoscale strain networks formed within a single prismatic (H) polytype monolayer of TaS2 created in situ on the surface of an orthorhombic 1T-TaS2 single crystal by a low-temperature laser-induced polytype transformation. The networks revealed by scanning tunneling microscopy (STM) take on diverse configurations at different temperatures, including extensive double stripes and a twisted 3-gonal mesh of connected 6-pronged vertices. The resulting phase diagram can be understood to be a consequence of thermally driven minimization of discommensurations between the H and 1T layers. Nontrivial dislocation defects of embedded 2- and 4-gonal structures are shown to be associated with local inhomogeneous strains. The creation of metastable heterostructures by laser quench at cryogenic temperatures in combination with STM manipulation of local strain demonstrates nanoscale control of topological defects in transition metal dichalcogenide heterostructures may be utilized in the fabrication of nanoscale electronic devices and neural networks.
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Affiliation(s)
- Jan Ravnik
- Complex
Matter Department, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Igor Vaskivskyi
- Center
of Excellence
on Nanoscience and Nanotechnology − Nanocenter (CENN Nanocenter), Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Yaroslav Gerasimenko
- Center
of Excellence
on Nanoscience and Nanotechnology − Nanocenter (CENN Nanocenter), Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Michele Diego
- Complex
Matter Department, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Jaka Vodeb
- Complex
Matter Department, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Viktor Kabanov
- Complex
Matter Department, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Dragan D. Mihailovic
- Complex
Matter Department, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Center
of Excellence
on Nanoscience and Nanotechnology − Nanocenter (CENN Nanocenter), Jamova 39, SI-1000 Ljubljana, Slovenia
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92
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Li L, Chen C, Watanabe K, Taniguchi T, Zheng Y, Xu Z, Pereira VM, Loh KP, Castro Neto AH. Anomalous Quantum Metal in a 2D Crystalline Superconductor with Electronic Phase Nonuniformity. NANO LETTERS 2019; 19:4126-4133. [PMID: 31082262 DOI: 10.1021/acs.nanolett.9b01574] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The details of the superconducting to quantum metal transition (SQMT) at T = 0 are an open problem that invokes great interest in the nature of this exotic and unexpected ground state (Ephron et al., 1996; Mason and Kapitulnik, 1999; Chervenak and Valles, 2000). However, the SQMT was not yet investigated in a crystalline 2D superconductor with coexisting and fluctuating quantum orders. Here, we report the observation of a SQMT in 2D ion-gel-gated 1T-TiSe2 (Li et al., 2016) driven by a magnetic field. A field-induced crossover between Bose quantum metal and vortex quantum creeping with an increasing field is observed. We discuss the interplay between superconducting and CDW fluctuations (discommensurations) and their relation to the anomalous quantum metal (AQM) phase. From our findings, gate-tunable 1T-TiSe2 emerges as a privileged platform to scrutinize, in a controlled way, the details of the SQMT, the role of coexisting fluctuating orders and, ultimately, to obtain a deeper understanding of the fate of superconductivity in strictly two-dimensional crystals near zero temperature.
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Affiliation(s)
- Linjun Li
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Chuan Chen
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551
| | - Kenji Watanabe
- National Institute for Materials Science , Namiki 1-1, Tsukuba , Ibaraki 305-0044 , Japan
| | - Takashi Taniguchi
- National Institute for Materials Science , Namiki 1-1, Tsukuba , Ibaraki 305-0044 , Japan
| | - Yi Zheng
- Department of Physics , Zhejiang University , Hangzhou 310027 , China
| | - Zhuan Xu
- Department of Physics , Zhejiang University , Hangzhou 310027 , China
| | - Vitor M Pereira
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551
| | - Kian Ping Loh
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , Singapore 117543
| | - Antonio H Castro Neto
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551
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93
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Lin H, Zhu Q, Shu D, Lin D, Xu J, Huang X, Shi W, Xi X, Wang J, Gao L. Growth of environmentally stable transition metal selenide films. NATURE MATERIALS 2019; 18:602-607. [PMID: 30858568 DOI: 10.1038/s41563-019-0321-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 02/11/2019] [Indexed: 06/09/2023]
Abstract
Two-dimensional transition metal selenides (TMSs) possess fascinating physical properties. However, many as-prepared TMSs are environmentally unstable and limited in sample size, which greatly hinder their wide applications in high-performance electrical devices. Here we develop a general two-step vapour deposition method and successfully grow different TMS films with controllable thickness, wafer size and high quality. The superconductivity of the grown NbSe2 film is comparable with sheets exfoliated from bulk materials, and can maintain stability after a variety of harsh treatments, which are ascribed to the absence of oxygen during the whole growth process. Such environmental stability can greatly simplify the fabrication procedure for device applications, and should be of both fundamental and technological significance in developing TMS-based devices.
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Affiliation(s)
- Huihui Lin
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Qi Zhu
- Center of Electron Microscopy and State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
| | - Dajun Shu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Dongjing Lin
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Jie Xu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Xianlei Huang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Wei Shi
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Xiaoxiang Xi
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Jiangwei Wang
- Center of Electron Microscopy and State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China.
| | - Libo Gao
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
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94
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Wong PKJ, Zhang W, Bussolotti F, Yin X, Herng TS, Zhang L, Huang YL, Vinai G, Krishnamurthi S, Bukhvalov DW, Zheng YJ, Chua R, N'Diaye AT, Morton SA, Yang CY, Ou Yang KH, Torelli P, Chen W, Goh KEJ, Ding J, Lin MT, Brocks G, de Jong MP, Castro Neto AH, Wee ATS. Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1901185. [PMID: 30997712 DOI: 10.1002/adma.201901185] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 03/30/2019] [Indexed: 06/09/2023]
Abstract
Monolayer VSe2 , featuring both charge density wave and magnetism phenomena, represents a unique van der Waals magnet in the family of metallic 2D transition-metal dichalcogenides (2D-TMDs). Herein, by means of in situ microscopy and spectroscopic techniques, including scanning tunneling microscopy/spectroscopy, synchrotron X-ray and angle-resolved photoemission, and X-ray absorption, direct spectroscopic signatures are established, that identify the metallic 1T-phase and vanadium 3d1 electronic configuration in monolayer VSe2 grown on graphite by molecular-beam epitaxy. Element-specific X-ray magnetic circular dichroism, complemented with magnetic susceptibility measurements, further reveals monolayer VSe2 as a frustrated magnet, with its spins exhibiting subtle correlations, albeit in the absence of a long-range magnetic order down to 2 K and up to a 7 T magnetic field. This observation is attributed to the relative stability of the ferromagnetic and antiferromagnetic ground states, arising from its atomic-scale structural features, such as rotational disorders and edges. The results of this study extend the current understanding of metallic 2D-TMDs in the search for exotic low-dimensional quantum phenomena, and stimulate further theoretical and experimental studies on van der Waals monolayer magnets.
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Affiliation(s)
- Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Wen Zhang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Fabio Bussolotti
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*Star), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore
| | - Xinmao Yin
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Tun Seng Herng
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Lei Zhang
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Yu Li Huang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Giovanni Vinai
- Instituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S. Km 163.5, Trieste, I-34149, Italy
| | - Sridevi Krishnamurthi
- Computational Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands
| | - Danil W Bukhvalov
- College of Science, Institute of Materials Physics and Chemistry, Nanjing Forestry University, Nanjing, 210037, P. R. China
- Institute of Physics and Technology, Ural Federal University, Mira Street 19, 620002, Yekaterinburg, Russia
| | - Yu Jie Zheng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Rebekah Chua
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Alpha T N'Diaye
- Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Simon A Morton
- Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Chao-Yao Yang
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Kui-Hon Ou Yang
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Piero Torelli
- Instituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S. Km 163.5, Trieste, I-34149, Italy
| | - Wei Chen
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Department of Chemistry, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Kuan Eng Johnson Goh
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*Star), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore
| | - Jun Ding
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Minn-Tsong Lin
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Geert Brocks
- Computational Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands
| | - Michel P de Jong
- NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands
| | - Antonio H Castro Neto
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Andrew Thye Shen Wee
- Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
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95
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Wang Z, Chu L, Li L, Yang M, Wang J, Eda G, Loh KP. Modulating Charge Density Wave Order in a 1T-TaS 2/Black Phosphorus Heterostructure. NANO LETTERS 2019; 19:2840-2849. [PMID: 30929451 DOI: 10.1021/acs.nanolett.8b04805] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Controllability of collective electron states has been a long-sought scientific and technological goal and promises development of new devices. Herein, we investigate the tuning of charge density wave (CDW) in 1T-TaS2 via a two-dimensional (2D) van der Waals heterostructure of 1T-TaS2/BP. Unusual gate-dependent conductance oscillations were observed in 1T-TaS2 nanoflake supported on BP in transport measurements. Scanning tunneling microscopy study shows that the nearly commensurate (NC) CDW phase survived to 4.5 K in this system, which is substantially lower than the NC to commensurate CDW phase transition temperature of 180 K. A Coulomb blockade model was invoked to explain the conductance oscillations, where the domain walls and domains in NC phase serve as series of quantum dot arrays and tunnelling barriers, respectively. Density functional theory calculations show that a range of interfacial interactions, including strain and charge transfer, influences the CDW stabilities. Our work sheds light on tuning CDW orders via 2D heterostructure stacking and provides new insights on the CDW phase transition and sliding mechanism.
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Affiliation(s)
- Ziying Wang
- Department of Chemistry , National University of Singapore , Singapore 117543
- Centre for Advanced 2D Materials , National University of Singapore, Singapore 117546
| | - Leiqiang Chu
- Department of Chemistry , National University of Singapore , Singapore 117543
- Centre for Advanced 2D Materials , National University of Singapore, Singapore 117546
| | - Linjun Li
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering , Zhejiang University , Hangzhou , China 310027
| | - Ming Yang
- Institute of Materials Research and Engineering, Agency for Science Technology and Research , 2 Fusionopolis Way , Singapore 138634
| | - Junyong Wang
- Centre for Advanced 2D Materials , National University of Singapore, Singapore 117546
- Department of Physics , National University of Singapore, Singapore 117542
| | - Goki Eda
- Department of Chemistry , National University of Singapore , Singapore 117543
- Centre for Advanced 2D Materials , National University of Singapore, Singapore 117546
- Department of Physics , National University of Singapore, Singapore 117542
| | - Kian Ping Loh
- Department of Chemistry , National University of Singapore , Singapore 117543
- Centre for Advanced 2D Materials , National University of Singapore, Singapore 117546
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96
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Zhang Z, Yang P, Hong M, Jiang S, Zhao G, Shi J, Xie Q, Zhang Y. Recent progress in the controlled synthesis of 2D metallic transition metal dichalcogenides. NANOTECHNOLOGY 2019; 30:182002. [PMID: 30650401 DOI: 10.1088/1361-6528/aaff19] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs), the complement of 2D semiconducting TMDCs, have attracted extensive attentions in recent years because of their versatile properties such as superconductivity, charge density wave, and magnetism. To promote the investigations of their fantastic properties and broad applications, the preparation of large-area, high-quality, and thickness-tunable 2D MTMDCs has become a very urgent topic and great efforts have been made. This topical review therefore focuses on the introduction of the recent achievements for the controllable syntheses of 2D MTMDCs (VS2, VSe2, TaS2, TaSe2, NbS2, NbSe2, etc). To begin with, some earlier developed routes such as chemical vapor transport, mechanical/chemical exfoliation, as well as molecular beam epitaxy methods are briefly introduced. Secondly, the scalable chemical vapor deposition methods involved with two sorts of metal-based feedstocks, including transition metal chlorides and transition metal oxidations mixed with alkali halides, are discussed separately. Finally, challenges for the syntheses of high-quality 2D MTMDCs are discussed and the future research directions in the related fields are proposed.
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Affiliation(s)
- Zhepeng Zhang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, People's Republic of China. Center for Nanochemistry (CNC), College of Chemistry and Molecular Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
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97
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Zhang C, Ni Z, Zhang J, Yuan X, Liu Y, Zou Y, Liao Z, Du Y, Narayan A, Zhang H, Gu T, Zhu X, Pi L, Sanvito S, Han X, Zou J, Shi Y, Wan X, Savrasov SY, Xiu F. Ultrahigh conductivity in Weyl semimetal NbAs nanobelts. NATURE MATERIALS 2019; 18:482-488. [PMID: 30886399 DOI: 10.1038/s41563-019-0320-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 02/11/2019] [Indexed: 06/09/2023]
Abstract
In two-dimensional (2D) systems, high mobility is typically achieved in low-carrier-density semiconductors and semimetals. Here, we discover that the nanobelts of Weyl semimetal NbAs maintain a high mobility even in the presence of a high sheet carrier density. We develop a growth scheme to synthesize single crystalline NbAs nanobelts with tunable Fermi levels. Owing to a large surface-to-bulk ratio, we argue that a 2D surface state gives rise to the high sheet carrier density, even though the bulk Fermi level is located near the Weyl nodes. A surface sheet conductance up to 5-100 S per □ is realized, exceeding that of conventional 2D electron gases, quasi-2D metal films, and topological insulator surface states. Corroborated by theory, we attribute the origin of the ultrahigh conductance to the disorder-tolerant Fermi arcs. The evidenced low-dissipation property of Fermi arcs has implications for both fundamental study and potential electronic applications.
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Affiliation(s)
- Cheng Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
| | - Zhuoliang Ni
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
| | - Jinglei Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei, China
| | - Xiang Yuan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
| | - Yanwen Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
| | - Yichao Zou
- Materials Engineering, The University of Queensland, Brisbane, Queensland, Australia
| | - Zhiming Liao
- Materials Engineering, The University of Queensland, Brisbane, Queensland, Australia
| | - Yongping Du
- Department of Applied Physics and Institution of Energy and Microstructure, Nanjing University of Science and Technology, Nanjing, China
| | | | - Hongming Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
| | - Tiancheng Gu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
| | - Xuesong Zhu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
| | - Li Pi
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei, China
| | - Stefano Sanvito
- School of Physics and CRANN Institute, Trinity College, Dublin, Ireland
| | - Xiaodong Han
- Beijing Key Laboratory and Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing, China
| | - Jin Zou
- Materials Engineering, The University of Queensland, Brisbane, Queensland, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland, Australia
| | - Yi Shi
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
- School of Electronic Science and Engineering, Nanjing University, Nanjing, China
| | - Xiangang Wan
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, China
| | - Sergey Y Savrasov
- Department of Physics, University of California, Davis, Davis, CA, USA
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, China.
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai, China.
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98
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Piatti E, Romanin D, Gonnelli RS. Mapping multi-valley Lifshitz transitions induced by field-effect doping in strained MoS 2 nanolayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:114002. [PMID: 30562728 DOI: 10.1088/1361-648x/aaf981] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Gate-induced superconductivity at the surface of nanolayers of semiconducting transition metal dichalcogenides (TMDs) has attracted a lot of attention in recent years, thanks to the sizeable transition temperature, robustness against in-plane magnetic fields beyond the Pauli limit, and hints to a non-conventional nature of the pairing. A key information necessary to unveil its microscopic origin is the geometry of the Fermi surface hosting the Cooper pairs as a function of field-effect doping, which is dictated by the filling of the inequivalent valleys at the K/K[Formula: see text] and Q/Q[Formula: see text] points of the Brillouin zone. Here, we achieve this by combining density functional theory calculations of the bandstructure with transport measurements on ion-gated 2H-MoS2 nanolayers. We show that, when the number of layers and the amount of strain are set to their experimental values, the Fermi level crosses the bottom of the high-energy valleys at Q/Q[Formula: see text] at doping levels where characteristic kinks in the transconductance are experimentally detected. We also develop a simple 2D model which is able to quantitatively describe the broadening of the kinks observed upon increasing temperature. We demonstrate that this combined approach can be employed to map the dependence of the Fermi surface of TMD nanolayers on field-effect doping, detect Lifshitz transitions, and provide a method to determine the amount of strain and spin-orbit splitting between sub-bands from electric transport measurements in real devices.
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Affiliation(s)
- Erik Piatti
- Department of Applied Science and Technology, Politecnico di Torino, 10129 Torino, Italy
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99
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Hu J, Zhang L, Song H, Hu J, Lv Y. Ratiometric Cataluminescence for Rapid Recognition of Volatile Organic Compounds Based on Energy Transfer Process. Anal Chem 2019; 91:4860-4867. [DOI: 10.1021/acs.analchem.9b00592] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Jiaxi Hu
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Lichun Zhang
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Hongjie Song
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Jianyu Hu
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Yi Lv
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
- Analytical and Testing Center, Sichuan University, Chengdu 610064, China
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100
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Hoesch M, Gannon L, Shimada K, Parrett BJ, Watson MD, Kim TK, Zhu X, Petrovic C. Disorder Quenching of the Charge Density Wave in ZrTe_{3}. PHYSICAL REVIEW LETTERS 2019; 122:017601. [PMID: 31012699 DOI: 10.1103/physrevlett.122.017601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 07/20/2018] [Indexed: 06/09/2023]
Abstract
The charge density wave (CDW) in ZrTe_{3} is quenched in samples with a small amount of Te isoelectronically substituted by Se. Using angle-resolved photoemission spectroscopy we observe subtle changes in the electronic band dispersions and Fermi surfaces upon Se substitution. The scattering rates are substantially increased, in particular for the large three-dimensional Fermi surface sheet. The quasi-one-dimensional band is unaffected by the substitution and still shows a gap at low temperature, which starts to open from room temperature. Long-range order is, however, absent in the electronic states as in the periodic lattice distortion. The competition between superconductivity and the CDW is thus linked to the suppression of long-range order of the CDW.
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Affiliation(s)
- Moritz Hoesch
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
- DESY Photon Science, Deutsches Elektronen-Synchrotron, Notekestrasse 85, 22607 Hamburg, Germany
| | - Liam Gannon
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
- Clarendon Laboratory, University of Oxford Physics Department, Parks Road, Oxford, OX1 3PU, United Kingdom
| | - Kenya Shimada
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
| | - Benjamin J Parrett
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street, London WC1 E6BT, United Kingdom
| | - Matthew D Watson
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
| | - Timur K Kim
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
| | - Xiangde Zhu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory Upton, New York 11973, USA
| | - Cedomir Petrovic
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory Upton, New York 11973, USA
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