1
|
Liu Y, Meng Q, Mahmoudi P, Wang Z, Zhang J, Yang J, Li W, Wang D, Li Z, Sorrell C, Li S. Advancing Superconductivity with Interface Engineering. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2405009. [PMID: 39104281 DOI: 10.1002/adma.202405009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 07/01/2024] [Indexed: 08/07/2024]
Abstract
The development of superconducting materials has attracted significant attention not only for their improved performance, such as high transition temperature (TC), but also for the exploration of their underlying physical mechanisms. Recently, considerable efforts have been focused on interfaces of materials, a distinct category capable of inducing superconductivity at non-superconducting material interfaces or augmenting the TC at the interface between a superconducting material and a non-superconducting material. Here, two distinct types of interfaces along with their unique characteristics are reviewed: interfacial superconductivity and interface-enhanced superconductivity, with a focus on the crucial factors and potential mechanisms responsible for enhancing superconducting performance. A series of materials systems is discussed, encompassing both historical developments and recent progress from the perspectives of technical innovations and the exploration of new material classes. The overarching goal is to illuminate pathways toward achieving high TC, expanding the potential of superconducting parameters across interfaces, and propelling superconductivity research toward practical, high-temperature applications.
Collapse
Affiliation(s)
- Yichen Liu
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Qingxiao Meng
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Pezhman Mahmoudi
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Ziyi Wang
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Ji Zhang
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Jack Yang
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Wenxian Li
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Danyang Wang
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Zhi Li
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Chris Sorrell
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Sean Li
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| |
Collapse
|
2
|
Chen AH, Lu Q, Hershkovitz E, Crespillo ML, Mazza AR, Smith T, Ward TZ, Eres G, Gandhi S, Mahfuz MM, Starchenko V, Hattar K, Lee JS, Kim H, Moore RG, Brahlek M. Interfacially Enhanced Superconductivity in Fe(Te,Se)/Bi 4Te 3 Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2401809. [PMID: 38717569 DOI: 10.1002/adma.202401809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/19/2024] [Indexed: 06/06/2024]
Abstract
Realizing topological superconductivity by integrating high-transition-temperature (TC) superconductors with topological insulators can open new paths for quantum computing applications. Here, a new approach is reported for increasing the superconducting transition temperature( T C onset ) $( {T_{\mathrm{C}}^{{\mathrm{onset}}}} )$ by interfacing the unconventional superconductor Fe(Te,Se) with the topological insulator Bi-Te system in the low-Se doping regime, near where superconductivity vanishes in the bulk. The critical finding is that theT C onset $T_{\mathrm{C}}^{{\mathrm{onset}}}$ of Fe(Te,Se) increases from nominally non-superconducting to as high as 12.5 K when Bi2Te3 is replaced with the topological phase Bi4Te3. Interfacing Fe(Te,Se) with Bi4Te3 is also found to be critical for stabilizing superconductivity in monolayer films whereT C onset $T_{\mathrm{C}}^{{\mathrm{onset}}}$ can be as high as 6 K. Measurements of the electronic and crystalline structure of the Bi4Te3 layer reveal that a large electron transfer, epitaxial strain, and novel chemical reduction processes are critical factors for the enhancement of superconductivity. This novel route for enhancing TC in an important epitaxial system provides new insight on the nature of interfacial superconductivity and a platform to identify and utilize new electronic phases.
Collapse
Affiliation(s)
- An-Hsi Chen
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Qiangsheng Lu
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Eitan Hershkovitz
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Miguel L Crespillo
- Department Nuclear Engineering, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Alessandro R Mazza
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Tyler Smith
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - T Zac Ward
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Gyula Eres
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Shornam Gandhi
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Meer Muhtasim Mahfuz
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Vitalii Starchenko
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Khalid Hattar
- Department Nuclear Engineering, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Joon Sue Lee
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Honggyu Kim
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Robert G Moore
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Matthew Brahlek
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| |
Collapse
|
3
|
Li Y, Xu L, Liu G, Fang Y, Zheng H, Dai S, Li E, Zhu G, Zhang S, Liang S, Yang L, Huang F, Xi X, Liu Z, Xu N, Chen Y. Evidence of strong and mode-selective electron-phonon coupling in the topological superconductor candidate 2M-WS 2. Nat Commun 2024; 15:6235. [PMID: 39043689 PMCID: PMC11266404 DOI: 10.1038/s41467-024-50590-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 07/12/2024] [Indexed: 07/25/2024] Open
Abstract
The interaction between lattice vibrations and electrons plays a key role in various aspects of condensed matter physics - including electron hydrodynamics, strange metal behavior, and high-temperature superconductivity. In this study, we present systematic investigations using Raman scattering and angle-resolved photoemission spectroscopy (ARPES) to examine the phononic and electronic subsystems of the topological superconductor candidate 2M-WS2. Raman scattering exhibits an anomalous nonmonotonic temperature dependence of phonon linewidths, indicative of strong phonon-electron scattering over phonon-phonon scattering. The ARPES results demonstrate pronounced dispersion anomalies (kinks) at multiple binding energies within both bulk and topological surface states, indicating a robust and mode-selective coupling between the electronic states and various phonon modes. These experimental findings align with previous calculations of the Eliashberg function, providing a deeper understanding of the highest superconducting transition temperature observed in 2M-WS2 (8.8 K) among all transition metal dichalcogenides as induced by electron-phonon coupling. Furthermore, our results may offer valuable insights into other properties of 2M-WS2 and guide the search for high-temperature topological superconductors.
Collapse
Affiliation(s)
- Yiwei Li
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, China.
| | - Lixuan Xu
- Department of Physics, Hubei University, Wuhan, China
| | - Gan Liu
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Yuqiang Fang
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Huijun Zheng
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, China
| | - Shenghao Dai
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, China
| | - Enting Li
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, China
| | - Guang Zhu
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, China
| | - Shihao Zhang
- School of Physics and Electronics, Hunan University, Changsha, China
| | - Shiheng Liang
- Department of Physics, Hubei University, Wuhan, China
| | - Lexian Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China
| | - Fuqiang Huang
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaoxiang Xi
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
| | - Zhongkai Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, China.
- ShanghaiTech Laboratory for Topological Physics, Shanghai, China.
| | - Nan Xu
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, China.
- Wuhan Institute of Quantum Technology, Wuhan, China.
| | - Yulin Chen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, China
- Department of Physics, University of Oxford, Oxford, UK
| |
Collapse
|
4
|
Guo N, Chen X, Yu T, Fan Y, Zhang Q, Lei M, Xu X, Zhu X, Guo J, Gu L, Xu H, Peng R, Feng D. Inferior Interfacial Superconductivity in 1 UC FeSe/SrVO 3/SrTiO 3 with Screened Interfacial Electron-Phonon Coupling. NANO LETTERS 2024; 24:8587-8594. [PMID: 38967395 DOI: 10.1021/acs.nanolett.4c01612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/06/2024]
Abstract
Single-unit cell (1 UC) FeSe interfaced with TiOx or FeOx exhibits significantly enhanced superconductivity compared to that of bulk FeSe, with interfacial electron-phonon coupling (EPC) playing a crucial role. However, the reduced dimensionality in 1 UC FeSe, which may drive superconducting fluctuations, complicates our understanding of the enhancement mechanisms. We construct a new superconducting interface, 1 UC FeSe/SrVO3/SrTiO3. Here, the itinerant electrons of highly metallic SrVO3 films can screen all high-energy Fuchs-Kliewer phonons, including those of SrTiO3, making it the first FeSe/oxide system with screened interfacial EPC while maintaining the 1 UC FeSe thickness. Despite comparable doping levels, the heavily electron-doped 1 UC FeSe/SrVO3 exhibits a pairing temperature (Tg ∼ 48 K) lower than those of FeSe/SrTiO3 and FeSe/LaFeO3. Our findings disentangle the contributions of interfacial EPC from dimensionality in terms of enhancing Tg in FeSe/oxide interfaces, underscoring the critical importance of interfacial EPC. This FeSe/VOx interface also provides a platform for studying interfacial superconductivity.
Collapse
Affiliation(s)
- Nan Guo
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Xiaoyang Chen
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Tianlun Yu
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yu Fan
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Minyinan Lei
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Xiaofeng Xu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xuetao Zhu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jiandong Guo
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Haichao Xu
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Rui Peng
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Donglai Feng
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
- National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China
- New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei 230026, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| |
Collapse
|
5
|
Li C, Song Y, Wang X, Lei M, Chen X, Xu H, Peng R, Feng D. Interface-Suppressed Nematicity and Enhanced Superconducting Pairing Strength of FeSe/NdFeO 3 in the Low-Doping Regime. NANO LETTERS 2024; 24:8303-8310. [PMID: 38934420 DOI: 10.1021/acs.nanolett.4c01493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
Abstract
The discovery of interfacial superconductivity in monolayer FeSe/oxides has spurred intensive research interest. Here we not only extend the FeSe/FeOx superconducting interface to FeSe/NdFeO3 but also establish robust interface-enhanced superconductivity at a very low doping level. Specifically, well-annealed FeSe/NdFeO3 exhibits a low doping level of 0.038-0.046 e-/Fe with a larger superconducting pairing gap without a nematic gap, indicating an enhancement of the enhanced superconducting pairing strength and suppression of nematicity by the FeSe/FeOx interface compared with those of thick FeSe films. These results improve our understanding of the roles of the oxide interface in the low-electron-doped regime.
Collapse
Affiliation(s)
- Chihao Li
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
| | - Yuanhe Song
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
| | - Xiaoxiao Wang
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
| | - Minyinan Lei
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
| | - Xiaoyang Chen
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
| | - Haichao Xu
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Rui Peng
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Donglai Feng
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
- National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China
- New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei 230026, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| |
Collapse
|
6
|
Ding C, Wei Z, Dong W, Feng H, Shi M, Wang L, Jia JF, Xue QK. Atomic-Site-Dependent Pairing Gap in Monolayer FeSe/SrTiO 3(001)-(√13 × √13). NANO LETTERS 2024; 24:8445-8452. [PMID: 38917425 DOI: 10.1021/acs.nanolett.4c02627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
The interfacial FeSe/TiO2-δ coupling induces high-temperature superconductivity in monolayer FeSe films. Using cryogenic atomically resolved scanning tunneling microscopy/spectroscopy, we obtained atomic-site dependent surface density of states, work function, and the pairing gap in the monolayer FeSe on the SrTiO3(001)-(√13 × √13)-R33.7° surface. Our results disclosed the out-of-plane Se-Fe-Se triple layer gradient variation, switched DOS for Fe sites on and off TiO5□, and inequivalent Fe sublattices, which gives global spatial modulation of pairing gap contaminants with the (√13 × √13) pattern. Moreover, the coherent lattice coupling induces strong inversion asymmetry and in-plane anisotropy in the monolayer FeSe, which is demonstrated to correlate with the particle-hole asymmetry in coherence peaks. These results disclose delicate atomic-scale correlations between pairing and lattice-electronic coupling in the Bardeen-Cooper-Schrieffer to Bose-Einstein condensation crossover regime, providing insights into understanding the pairing mechanism of multiorbital superconductivity.
Collapse
Affiliation(s)
- Cui Ding
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area, Shenzhen 518045, China
| | - Zhongxu Wei
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Wenfeng Dong
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Hai Feng
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Mingxia Shi
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Jin-Feng Jia
- Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area, Shenzhen 518045, China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area, Shenzhen 518045, China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| |
Collapse
|
7
|
Shi R, Li Q, Xu X, Han B, Zhu R, Liu F, Qi R, Zhang X, Du J, Chen J, Yu D, Zhu X, Guo J, Gao P. Atomic-scale observation of localized phonons at FeSe/SrTiO 3 interface. Nat Commun 2024; 15:3418. [PMID: 38653990 DOI: 10.1038/s41467-024-47688-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 04/03/2024] [Indexed: 04/25/2024] Open
Abstract
In single unit-cell FeSe grown on SrTiO3, the superconductivity transition temperature features a significant enhancement. Local phonon modes at the interface associated with electron-phonon coupling may play an important role in the interface-induced enhancement. However, such phonon modes have eluded direct experimental observations. The complicated atomic structure of the interface brings challenges to obtain the accurate structure-phonon relation knowledge. Here, we achieve direct characterizations of atomic structure and phonon modes at the FeSe/SrTiO3 interface with atomically resolved imaging and electron energy loss spectroscopy in an electron microscope. We find several phonon modes highly localized (~1.3 nm) at the unique double layer Ti-O terminated interface, one of which (~ 83 meV) engages in strong interactions with the electrons in FeSe based on ab initio calculations. This finding of the localized interfacial phonon associated with strong electron-phonon coupling provides new insights into understanding the origin of superconductivity enhancement at the FeSe/SrTiO3 interface.
Collapse
Affiliation(s)
- Ruochen Shi
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Qize Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Xiaofeng Xu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Bo Han
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Ruixue Zhu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Fachen Liu
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
| | - Ruishi Qi
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Xiaowen Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Jinlong Du
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Ji Chen
- Institute of Condensed Matter and Material Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing, 100871, China
| | - Dapeng Yu
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen, 518055, China
- Hefei National Laboratory, 230088, Hefei, China
| | - Xuetao Zhu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Jiandong Guo
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Peng Gao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China.
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China.
- Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China.
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing, 100871, China.
- Hefei National Laboratory, 230088, Hefei, China.
| |
Collapse
|
8
|
Zhao D, Cui W, Liu Y, Gong G, Zhang L, Jia G, Zang Y, Hu X, Zhang D, Wang Y, Li W, Ji S, Wang L, He K, Ma X, Xue QK. Electronic inhomogeneity and phase fluctuation in one-unit-cell FeSe films. Nat Commun 2024; 15:3369. [PMID: 38643171 PMCID: PMC11032316 DOI: 10.1038/s41467-024-47350-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 03/25/2024] [Indexed: 04/22/2024] Open
Abstract
One-unit-cell FeSe films on SrTiO3 substrates are of great interest owing to significantly enlarged pairing gaps characterized by two coherence peaks at ±10 meV and ±20 meV. In-situ transport measurement is desired to reveal novel properties. Here, we performed in-situ microscale electrical transport and combined scanning tunneling microscopy measurements on continuous one-unit-cell FeSe films with twin boundaries. We observed two spatially coexisting superconducting phases in domains and on boundaries, characterized by distinct superconducting gaps (Δ 1 ~15 meV vs.Δ 2 ~10 meV) and pairing temperatures (Tp1~52.0 K vs. Tp2~37.3 K), and correspondingly two-step nonlinear V ~ I α behavior but a concurrent Berezinskii-Kosterlitz-Thouless (BKT)-like transition occurring atT BKT ~28.7 K. Moreover, the onset transition temperatureT c onset ~54 K and zero-resistivity temperatureT c zero ~31 K are consistent with Tp1 andT BKT , respectively. Our results indicate the broadened superconducting transition in FeSe/SrTiO3 is related to intrinsic electronic inhomogeneity due to distinct two-gap features and phase fluctuations of two-dimensional superconductivity.
Collapse
Affiliation(s)
- Dapeng Zhao
- Beijing Academy of Quantum Information Sciences, 100193, Beijing, China
| | - Wenqiang Cui
- Beijing Academy of Quantum Information Sciences, 100193, Beijing, China
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China
| | - Yaowu Liu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China
| | - Guanming Gong
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China
| | - Liguo Zhang
- Beijing Academy of Quantum Information Sciences, 100193, Beijing, China
| | - Guihao Jia
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China
| | - Yunyi Zang
- Beijing Academy of Quantum Information Sciences, 100193, Beijing, China
| | - Xiaopeng Hu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China
| | - Ding Zhang
- Beijing Academy of Quantum Information Sciences, 100193, Beijing, China
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China
- Frontier Science Center for Quantum Information, 100084, Beijing, China
| | - Yilin Wang
- School of Integrated Circuits, Shandong Technology Center of Nanodevices and Integration, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China.
| | - Wei Li
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China
- Frontier Science Center for Quantum Information, 100084, Beijing, China
| | - Shuaihua Ji
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China
- Frontier Science Center for Quantum Information, 100084, Beijing, China
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China.
- Frontier Science Center for Quantum Information, 100084, Beijing, China.
| | - Ke He
- Beijing Academy of Quantum Information Sciences, 100193, Beijing, China
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China
- Frontier Science Center for Quantum Information, 100084, Beijing, China
| | - Xucun Ma
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China
- Frontier Science Center for Quantum Information, 100084, Beijing, China
| | - Qi-Kun Xue
- Beijing Academy of Quantum Information Sciences, 100193, Beijing, China.
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, 100084, Beijing, China.
- Frontier Science Center for Quantum Information, 100084, Beijing, China.
- Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China.
| |
Collapse
|
9
|
Jiao X, Dong W, Shi M, Wang H, Ding C, Wei Z, Gong G, Li Y, Li Y, Zuo B, Wang J, Zhang D, Pan M, Wang L, Xue QK. Significantly enhanced superconductivity in monolayer FeSe films on SrTiO 3(001) via metallic δ-doping. Natl Sci Rev 2024; 11:nwad213. [PMID: 38312379 PMCID: PMC10833465 DOI: 10.1093/nsr/nwad213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 07/19/2023] [Accepted: 07/25/2023] [Indexed: 02/06/2024] Open
Abstract
Superconductivity transition temperature (Tc) marks the inception of a macroscopic quantum phase-coherent paired state in fermionic systems. For 2D superconductivity, the paired electrons condense into a coherent superfluid state at Tc, which is usually lower than the pairing temperature, between which intrinsic physics including Berezinskii-Kosterlitz-Thouless transition and pseudogap state are hotly debated. In the case of monolayer FeSe superconducting films on SrTiO3(001), although the pairing temperature (Tp) is revealed to be 65-83 K by using spectroscopy characterization, the measured zero-resistance temperature ([Formula: see text]) is limited to 20 K. Here, we report significantly enhanced superconductivity in monolayer FeSe films by δ-doping of Eu or Al on SrTiO3(001) surface, in which [Formula: see text] is enhanced by 12 K with a narrowed transition width ΔTc ∼ 8 K, compared with non-doped samples. Using scanning tunneling microscopy/spectroscopy measurements, we demonstrate lowered work function of the δ-doped SrTiO3(001) surface and enlarged superconducting gaps in the monolayer FeSe with improved morphology/electronic homogeneity. Our work provides a practical route to enhance 2D superconductivity by using interface engineering.
Collapse
Affiliation(s)
- Xiaotong Jiao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- School of Physics & Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Wenfeng Dong
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Mingxia Shi
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Heng Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Cui Ding
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Zhongxu Wei
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Guanming Gong
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yanan Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Yuanzhao Li
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Binjie Zuo
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Jian Wang
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Hefei National Laboratory, Hefei 230088, China
| | - Ding Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Minghu Pan
- School of Physics & Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| |
Collapse
|
10
|
Lee Y, Kim Y, Lee S, Kim C. Ferromagnetic insulating substrate for magnetic proximity studies: LaCoO 3thin film. NANOTECHNOLOGY 2024; 35:125001. [PMID: 38064735 DOI: 10.1088/1361-6528/ad13bd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 12/08/2023] [Indexed: 01/05/2024]
Abstract
Ferromagnetic insulators (FMIs) are intriguing not only due to their rare nature, but also due to their potential applications in spintronics and various electronic devices. One of its key promising applications is based on an FMI-induced magnetic proximity effect, which can impose an effective time-reversal symmetry breaking on the target ultrathin layer to realize novel emergent phenomena. Here, we conduct systematic studies on thin film LaCoO3, an insulator known to be ferromagnet under tensile strain, with varying thicknesses, to establish it as an FMI platform to be integrated in heterostructures. The optimal thickness of the LaCoO3layer, providing a smooth surface and robust ferromagnetism with large remanence, is determined. A heterostructure consisting of an ultrathin target layer (2 uc SrRuO3), the LaCoO3FMI layer, and the La0.5Sr0.5CoO3conducting layer has been fabricated and the angle-resolved photoemission spectroscopy measurement on the multi-layer system demonstrates a sharp Fermi edge and a well-defined Fermi surface without the charging effect. This demonstrates the feasibility of the proposed heterostructure using LaCoO3thin film as the FMI layer, and further lays a groundwork to investigate the magnetic proximity induced phases in quantum materials.
Collapse
Affiliation(s)
- Yeonjae Lee
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Youngdo Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Sangjae Lee
- The Research Institute of Basic Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| |
Collapse
|
11
|
Xue CL, Dou LG, Xu YJ, Yuan QQ, Li QY, Jia ZY, Li Z, Liu R, Li SC. Iron Vacancy Tunable Superconductor-Insulator Transition in FeSe/SrTiO_{3} Monolayer. PHYSICAL REVIEW LETTERS 2023; 131:256002. [PMID: 38181352 DOI: 10.1103/physrevlett.131.256002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 11/15/2023] [Accepted: 11/21/2023] [Indexed: 01/07/2024]
Abstract
The Fe_{4}Se_{5} with a sqrt[5]×sqrt[5] Fe vacancy order is suggested to be a Mott insulator and the parent state of bulk FeSe superconductor. The iron vacancy ordered state has been considered as a Mott insulator and the parent compound of bulk FeSe-based superconductors. However, for the superconducting FeSe/SrTiO_{3} monolayer (FeSe/STO) with an interface-enhanced high transition temperature (T_{c}), the electronic evolution from its Fe vacancy ordered parent phase to the superconducting state, has not been explored due to the challenge to realize an Fe vacancy order in the FeSe/STO monolayer, even though important to the understanding of superconductivity mechanism. In this study, we developed a new method to generate Fe vacancies within the FeSe/STO monolayer in a tunable fashion, with the assistance of atomic hydrogen. As a consequence, an insulating sqrt[5]×sqrt[5] Fe vacancy ordered monolayer is realized as the parent state. By using scanning tunneling microscopy and scanning tunneling spectroscopy, the spectral evolution from superconductivity to insulator is fully characterized. Surprisingly, a prominent spectral weight transfer occurs, thus implying a strong electron correlation effect. Moreover, the Fe vacancy induced insulating gap exhibits no Mott gap-like features. This work provides new insights in understanding the high-T_{c} superconductivity in FeSe/STO monolayer.
Collapse
Affiliation(s)
- Cheng-Long Xue
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Li-Guo Dou
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Yong-Jie Xu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Qian-Qian Yuan
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Qi-Yuan Li
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Zhen-Yu Jia
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Zishuang Li
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Ronghua Liu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory for Nanotechnology, Nanjing University, Nanjing 210093, China
| | - Shao-Chun Li
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory for Nanotechnology, Nanjing University, Nanjing 210093, China
- Hefei National Laboratory, Hefei 230088, China
| |
Collapse
|
12
|
Liu Y, Wang A, Du Q, Wu L, Zhu Y, Petrovic C. Nanoscale inhomogeneity and the evolution of correlation strength in FeSe[Formula: see text]S[Formula: see text]. NANO CONVERGENCE 2023; 10:59. [PMID: 38133699 PMCID: PMC10746694 DOI: 10.1186/s40580-023-00405-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 11/26/2023] [Indexed: 12/23/2023]
Abstract
We report a comprehensive study of the nanoscale inhomogeneity and disorder on the thermoelectric properties of FeSe[Formula: see text]S[Formula: see text] ([Formula: see text]) single crystals and the evolution of correlation strength with S substitution. A hump-like feature in temperature-dependent thermpower is enhanced for x = 0.12 and 0.14 in the nematic region with increasing in orbital-selective electronic correlations, which is strongly suppressed across the nematic critical point and for higher S content. Nanoscale Se/S atom disorder in the tetrahedral surroundings of Fe atoms is confirmed by scanning transmission electron microscopy measurements, providing an insight into the nanostructural details and the evolution of correlation strength in FeSe[Formula: see text]S[Formula: see text].
Collapse
Affiliation(s)
- Yu Liu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973 USA
- Center for Correlated Matter and School of Physics, Zhejiang University, Hangzhou, 310058 China
| | - Aifeng Wang
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973 USA
- Present Address: College of Physics, Chongqing University, Chongqing, 401331 China
| | - Qianheng Du
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973 USA
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NeY 11790 USA
- Present Address: Material Science Division, Argonne National Laboratory, Lemont, IL 60439 USA
| | - Lijun Wu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973 USA
| | - Yimei Zhu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973 USA
| | - Cedomir Petrovic
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973 USA
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NeY 11790 USA
| |
Collapse
|
13
|
Zou X, Xie M, Wang R, Liang H, Li Y, Tian F, Sun Y, Wang C. Two-Dimensional Superconductivity in Air-Stable Single-Crystal Few-Layer Bi 3O 2S 3. J Am Chem Soc 2023; 145:20975-20984. [PMID: 37703097 DOI: 10.1021/jacs.3c06854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
The progress of unconventional superconductors at the two-dimensional (2D) limit has inspired much interest. Recently, a new superconducting system was discovered in the semimetallic ternary Bi-O-S family. However, pure-phase crystals are difficult to synthesize because of the complicated stacking sequence of multiple charged layers and similar formation kinetics among ternary polytypes, leaving several fundamental issues regarding the structure-superconductivity correlation unresolved. Herein, 2D single-crystal ultrathin Bi3O2S3 nanosheets are prepared by using low-pressure chemical vapor deposition, and their atomic arrangement is clarified. Magnetotransport measurements indicate a superconducting transition at ∼6.1 K that is thickness-independent. The transport results demonstrate 2D superconducting characteristics, such as the Berezinskii-Kosterlitz-Thouless transition, and strong anisotropy with magnetic field orientations following the 2D Tinkham formula. The difference from superconductivity of powder is demonstrated from the perspective of their corresponding microstructures. These results corroborate the superconducting behavior of Bi3O2S3, providing fresh insights into the search for other bismuth oxychalcogenides and derivative BiS2-based analogues at the 2D limit.
Collapse
Affiliation(s)
- Xiaobin Zou
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Mingyuan Xie
- School of Physics, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Ruize Wang
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Haikuan Liang
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Yan Li
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Fei Tian
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Yong Sun
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Chengxin Wang
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| |
Collapse
|
14
|
Yang H, Zhou Y, Miao G, Xu X, Han X, Zhu XX, Guo J, Wu R, Pan X. Role of Substrate Phonon in the Electron-phonon Coupling at FeSe/SrTiO3 Interface. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1629-1630. [PMID: 37613836 DOI: 10.1093/micmic/ozad067.837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Hongbin Yang
- Department of Materials Science and Engineering, University of California, Irvine, CA, USA
| | - Yinong Zhou
- Department of Physics and Astronomy, University of California, Irvine, CA, USA
| | - Guangyao Miao
- Insititue of Physics, Chinese Academy of Sciences, Beijing, China
| | - Xiaofeng Xu
- Insititue of Physics, Chinese Academy of Sciences, Beijing, China
| | - Xiang Han
- Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Xu Xuetao Zhu
- Insititue of Physics, Chinese Academy of Sciences, Beijing, China
| | - Jiandong Guo
- Insititue of Physics, Chinese Academy of Sciences, Beijing, China
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, CA, USA
| | - Xiaoqing Pan
- Department of Materials Science and Engineering, University of California, Irvine, CA, USA
- Department of Physics and Astronomy, University of California, Irvine, CA, USA
- Irvine Materials Research Institute (IMRI), University of California, Irvine, CA, USA
| |
Collapse
|
15
|
Kobayashi T, Nakagawa H, Ogawa H, Nabeshima F, Maeda A. Anisotropy of upper critical fields and interface superconductivity in FeSe/SrTiO 3grown by PLD. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:41LT01. [PMID: 37402379 DOI: 10.1088/1361-648x/ace410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 07/04/2023] [Indexed: 07/06/2023]
Abstract
In this study, we grow FeSe/SrTiO3with thicknesses of 4-19 nm using pulsed laser deposition and investigate their magneto-transport properties. The thinnest film (4 nm) exhibit negative Hall effect, indicating electron transfer into FeSe from the SrTiO3substrate. This is in agreement with reports on ultrathin FeSe/SrTiO3grown by molecular beam epitaxy. The upper critical field is found to exhibit large anisotropy (γ>11.9), estimated from the data near the transition temperature (Tc). In particular, the estimated coherence lengths in the perpendicular direction are 0.15-0.27 nm, which are smaller than thec-axis length of FeSe, and are found to be almost independent of the total thicknesses of the films. These results indicate that superconductivity is confined at the interface of FeSe/SrTiO3.
Collapse
Affiliation(s)
- Tomoki Kobayashi
- Department of Basic Science, University of Tokyo, Meguro 153-8902, Tokyo, Japan
| | - Hiroki Nakagawa
- Department of Basic Science, University of Tokyo, Meguro 153-8902, Tokyo, Japan
| | - Hiroki Ogawa
- Department of Basic Science, University of Tokyo, Meguro 153-8902, Tokyo, Japan
| | - Fuyuki Nabeshima
- Department of Basic Science, University of Tokyo, Meguro 153-8902, Tokyo, Japan
| | - Atsutaka Maeda
- Department of Basic Science, University of Tokyo, Meguro 153-8902, Tokyo, Japan
| |
Collapse
|
16
|
Moore RG, Lu Q, Jeon H, Yao X, Smith T, Pai YY, Chilcote M, Miao H, Okamoto S, Li AP, Oh S, Brahlek M. Monolayer Superconductivity and Tunable Topological Electronic Structure at the Fe(Te,Se)/Bi 2 Te 3 Interface. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2210940. [PMID: 36921318 DOI: 10.1002/adma.202210940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 03/07/2023] [Indexed: 06/02/2023]
Abstract
The interface between 2D topological Dirac states and an s-wave superconductor is expected to support Majorana-bound states (MBS) that can be used for quantum computing applications. Realizing these novel states of matter and their applications requires control over superconductivity and spin-orbit coupling to achieve spin-momentum-locked topological interface states (TIS) which are simultaneously superconducting. While signatures of MBS have been observed in the magnetic vortex cores of bulk FeTe0.55 Se0.45 , inhomogeneity and disorder from doping make these signatures unclear and inconsistent between vortices. Here superconductivity is reported in monolayer (ML) FeTe1-y Sey (Fe(Te,Se)) grown on Bi2 Te3 by molecular beam epitaxy (MBE). Spin and angle-resolved photoemission spectroscopy (SARPES) directly resolve the interfacial spin and electronic structure of Fe(Te,Se)/Bi2 Te3 heterostructures. For y = 0.25, the Fe(Te,Se) electronic structure is found to overlap with the Bi2 Te3 TIS and the desired spin-momentum locking is not observed. In contrast, for y = 0.1, reduced inhomogeneity measured by scanning tunneling microscopy (STM) and a smaller Fe(Te,Se) Fermi surface with clear spin-momentum locking in the topological states are found. Hence, it is demonstrated that the Fe(Te,Se)/Bi2 Te3 system is a highly tunable platform for realizing MBS where reduced doping can improve characteristics important for Majorana interrogation and potential applications.
Collapse
Affiliation(s)
- Robert G Moore
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Qiangsheng Lu
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Hoyeon Jeon
- Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Xiong Yao
- Department of Physics and Astronomy, Rutgers the State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Tyler Smith
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Yun-Yi Pai
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Michael Chilcote
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Hu Miao
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Satoshi Okamoto
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - An-Ping Li
- Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Seongshik Oh
- Department of Physics and Astronomy, Rutgers the State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Matthew Brahlek
- Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| |
Collapse
|
17
|
Guo Y, Qiu D, Shao M, Song J, Wang Y, Xu M, Yang C, Li P, Liu H, Xiong J. Modulations in Superconductors: Probes of Underlying Physics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209457. [PMID: 36504310 DOI: 10.1002/adma.202209457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/16/2022] [Indexed: 06/02/2023]
Abstract
The importance of modulations is elevated to an unprecedented level, due to the delicate conditions required to bring out exotic phenomena in quantum materials, such as topological materials, magnetic materials, and superconductors. Recently, state-of-the-art modulation techniques in material science, such as electric-double-layer transistor, piezoelectric-based strain apparatus, angle twisting, and nanofabrication, have been utilized in superconductors. They not only efficiently increase the tuning capability to the broader ranges but also extend the tuning dimensionality to unprecedented degrees of freedom, including quantum fluctuations of competing phases, electronic correlation, and phase coherence essential to global superconductivity. Here, for a comprehensive review, these techniques together with the established modulation methods, such as elemental substitution, annealing, and polarization-induced gating, are contextualized. Depending on the mechanism of each method, the modulations are categorized into stoichiometric manipulation, electrostatic gating, mechanical modulation, and geometrical design. Their recent advances are highlighted by applications in newly discovered superconductors, e.g., nickelates, Kagome metals, and magic-angle graphene. Overall, the review is to provide systematic modulations in emergent superconductors and serve as the coordinate for future investigations, which can stimulate researchers in superconductivity and other fields to perform various modulations toward a thorough understanding of quantum materials.
Collapse
Affiliation(s)
- Yehao Guo
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Dong Qiu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Mingxin Shao
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Jingyan Song
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Yang Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Minyi Xu
- 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
| | - Peng Li
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Haiwen Liu
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Jie Xiong
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| |
Collapse
|
18
|
Zhou JS, Xu RZ, Yu XQ, Cheng FJ, Zhao WX, Du X, Wang SZ, Zhang QQ, Gu X, He SM, Li YD, Ren MQ, Ma XC, Xue QK, Chen YL, Song CL, Yang LX. Evidence for Band Renormalizations in Strong-Coupling Superconducting Alkali-Fulleride Films. PHYSICAL REVIEW LETTERS 2023; 130:216004. [PMID: 37295091 DOI: 10.1103/physrevlett.130.216004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 02/06/2023] [Accepted: 04/17/2023] [Indexed: 06/12/2023]
Abstract
There has been a long-standing debate about the mechanism of the unusual superconductivity in alkali-intercalated fullerides. In this Letter, using high-resolution angle-resolved photoemission spectroscopy, we systematically investigate the electronic structures of superconducting K_{3}C_{60} thin films. We observe a dispersive energy band crossing the Fermi level with the occupied bandwidth of about 130 meV. The measured band structure shows prominent quasiparticle kinks and a replica band involving the Jahn-Teller active phonon modes, which reflects strong electron-phonon coupling in the system. The electron-phonon coupling constant is estimated to be about 1.2, which dominates the quasiparticle mass renormalization. Moreover, we observe an isotropic nodeless superconducting gap beyond the mean-field estimation (2Δ/k_{B}T_{c}≈5). Both the large electron-phonon coupling constant and large reduced superconducting gap suggest a strong-coupling superconductivity in K_{3}C_{60}, while the electronic correlation effect is suggested by the observation of a waterfall-like band dispersion and the small bandwidth compared with the effective Coulomb interaction. Our results not only directly visualize the crucial band structure but also provide important insights into the mechanism of the unusual superconductivity of fulleride compounds.
Collapse
Affiliation(s)
- J S Zhou
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - R Z Xu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - X Q Yu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - F J Cheng
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - W X Zhao
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - X Du
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - S Z Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Q Q Zhang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - X Gu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - S M He
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Y D Li
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - M Q Ren
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - X C Ma
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Q K Xue
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Y L Chen
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
- School of Physical Science and Technology, ShanghaiTech University and CAS-Shanghai Science Research Center, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
| | - C L Song
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - L X Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| |
Collapse
|
19
|
Zou Q, Oli BD, Zhang H, Benigno J, Li X, Li L. Deciphering Alloy Composition in Superconducting Single-Layer FeSe 1-xS x on SrTiO 3(001) Substrates by Machine Learning of STM/S Data. ACS APPLIED MATERIALS & INTERFACES 2023; 15:22644-22650. [PMID: 37125966 PMCID: PMC10176460 DOI: 10.1021/acsami.2c23324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Scanning tunneling microscopy (STM) is a powerful technique for imaging atomic structure and inferring information on local elemental composition, chemical bonding, and electronic excitations. However, a plain visual analysis of STM images can be challenging for such determination in multicomponent alloys, particularly beyond the diluted limit due to chemical disorder and electronic inhomogeneity. One viable solution is to use machine learning to analyze STM data and identify hidden patterns and correlations. Here, we apply this approach to determine the Se/S concentration in superconducting single-layer FeSe1-xSx alloys epitaxially grown on SrTiO3(001) substrates via molecular beam epitaxy. First, the K-means clustering method is applied to identify defect-related dI/dV tunneling spectra taken by current imaging tunneling spectroscopy. Then, the Se/S ratio is calculated by analyzing the remaining spectra based on the singular value decomposition method. Such analysis provides an efficient and reliable determination of alloy composition and further reveals the correlations of nanoscale chemical inhomogeneity to superconductivity in single-layer iron chalcogenide films.
Collapse
Affiliation(s)
- Qiang Zou
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Basu Dev Oli
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Huimin Zhang
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Joseph Benigno
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Xin Li
- Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Lian Li
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| |
Collapse
|
20
|
Zakeri K, Rau D, Jandke J, Yang F, Wulfhekel W, Berthod C. Direct Probing of a Large Spin-Orbit Coupling in the FeSe Superconducting Monolayer on STO. ACS NANO 2023; 17:9575-9585. [PMID: 37155694 DOI: 10.1021/acsnano.3c02876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Spin-orbit coupling (SOC) is a fundamental physical interaction, which describes how the electrons' spin couples to their orbital motion. It is the source of a vast variety of fascinating phenomena in nanostructures. Although in most theoretical descriptions of high-temperature superconductivity SOC has been neglected, including this interaction can, in principle, revise the microscopic picture. Here by preforming energy-, momentum-, and spin-resolved spectroscopy experiments we demonstrate that while probing the dynamic charge response of the FeSe monolayer on strontium titanate, a prototype two-dimensional high-temperature superconductor using electrons, the scattering cross-section is spin dependent. We unravel the origin of the observed phenomenon and show that SOC in this two-dimensional superconductor is strong. We anticipate that such a strong SOC can have several consequences on the electronic structures and may compete with other pairing scenarios and be crucial for the mechanism of superconductivity.
Collapse
Affiliation(s)
- Khalil Zakeri
- Heisenberg Spin-dynamics Group, Physikalisches Institut, Karlsruhe Institute of Technology, Wolfgang-Gaede-Straße 1, D-76131 Karlsruhe, Germany
| | - Dominik Rau
- Heisenberg Spin-dynamics Group, Physikalisches Institut, Karlsruhe Institute of Technology, Wolfgang-Gaede-Straße 1, D-76131 Karlsruhe, Germany
| | - Jasmin Jandke
- Physikalisches Institut, Karlsruhe Institute of Technology, Wolfgang-Gaede-Straße 1, D-76131 Karlsruhe, Germany
| | - Fang Yang
- Physikalisches Institut, Karlsruhe Institute of Technology, Wolfgang-Gaede-Straße 1, D-76131 Karlsruhe, Germany
| | - Wulf Wulfhekel
- Physikalisches Institut, Karlsruhe Institute of Technology, Wolfgang-Gaede-Straße 1, D-76131 Karlsruhe, Germany
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, D-76344, Eggenstein-Leopoldshafen, Germany
| | - Christophe Berthod
- Department of Quantum Matter Physics, University of Geneva, 1211 Geneva, Switzerland
| |
Collapse
|
21
|
Xiang M, Ma X, Gao C, Guo Z, Huang C, Xing Y, Tan S, Zhao J, Wang B, Shao X. Revealing the Polaron State at the MoS 2/TiO 2 Interface. J Phys Chem Lett 2023; 14:3360-3367. [PMID: 36995045 DOI: 10.1021/acs.jpclett.2c03856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Interfacial polarons determine the distribution of free charges at the interface and thus play important roles in manipulating the physicochemical properties of hybridized polaronic materials. In this work, we investigated the electronic structures at the atomically flat interface of the single-layer MoS2 (SL-MoS2) on the rutile TiO2 surface using high-resolution angle-resolved photoemission spectroscopy. Our experiments directly visualized both the valence band maximum and the conduction band minimum (CBM) of SL-MoS2 at the K point, which clearly defines a direct bandgap of ∼2.0 eV. Detailed analyses corroborated by density functional theory calculations demonstrated that the CBM of MoS2 is formed by the trapped electrons at the MoS2/TiO2 interface that couple with the longitudinal optical phonons in the TiO2 substrate through an interfacial Fröhlich polaron state. Such an interfacial coupling effect may register a new route for tuning the free charges in the hybridized systems of two-dimensional materials and functional metal oxides.
Collapse
|
22
|
Yang Y, Jia L, Wang D, Zhou J. Advanced Strategies in Synthesis of Two-Dimensional Materials with Different Compositions and Phases. SMALL METHODS 2023; 7:e2201585. [PMID: 36739597 DOI: 10.1002/smtd.202201585] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/28/2022] [Indexed: 06/18/2023]
Abstract
In recent years, 2D materials-Ma Xb with different compositions and phases have attracted tremendous attention due to their diverse structures and electronic features. The common thermodynamically stable 2H and metastable 1T phases have been extensively studied, however, there are many unusual compositions and phases with novel physical properties that have yet to be explored. Therefore, summarization of the synthesis strategies, atomic structures, and the unique physical properties of 2D materials with different compositions and phases is very important for their development. In this review, the strategies including chemical vapor deposition, intercalation, atomic layer deposition, chemical vapor transport, and electrostatic gating for synthesizing various 2D materials with different phases and compositions are first summarized. Specially, the intercalation strategies including heterogeneous- and self-intercalation for controllable phases and compositions fabrication are mainly discussed. Then, the novel atomic structures of 2D materials are analyzed, followed by the fascinating physical properties including ferroelectricity, ferromagnetism, superconductivity, and so on. Finally, the conclusion and outlook are offered including the challenges and future prospects of 2D materials with different compositions and phases.
Collapse
Affiliation(s)
- Yang Yang
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Lin Jia
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Dainan Wang
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Jiadong Zhou
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
- MIIT Key Laboratory of Complex-field Intelligent Exploration, Beijing Institute of Technology, Beijing, 100081, China
| |
Collapse
|
23
|
Tomassucci G, Tortora L, Pugliese GM, Stramaglia F, Simonelli L, Marini C, Terashima K, Wakita T, Ayukawa S, Yokoya T, Kudo K, Nohara M, Mizokawa T, Saini NL. Temperature dependent local inhomogeneity and magnetic moments of (Li 1-xFe x)OHFeSe superconductors. Phys Chem Chem Phys 2023; 25:6684-6692. [PMID: 36806473 DOI: 10.1039/d3cp00004d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have combined the extended X-ray absorption fine structure (EXAFS) and X-ray emission spectroscopy (XES) to investigate the local structure and the local iron magnetic moments of (Li1-xFex)OHFeSe (x∼0.2) superconductors. The local structure, studied by Fe K-edge EXAFS measurements, is found to be inhomogeneous that is characterized by different Fe-Se bond lengths. The inhomogeneous phase exhibits a peculiar temperature dependence with lattice anomalies in the local structural parameters at the critical temperature Tc (36 K) and at the spin density wave (SDW) transition temperature TN (130 K). Fe Kβ XES shows iron to be in a low spin state with the local Fe magnetic moment evolving anomalously as a function of temperature. Apart from a quantitative measurement of the local structure of (Li1-xFex)OHFeSe, providing direct evidence of nanoscale inhomogeneity, the results provide further evidence of the vital role that the coupled electronic, lattice and magnetic degrees of freedom play in the iron-based superconductors.
Collapse
Affiliation(s)
- G Tomassucci
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| | - L Tortora
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| | - G M Pugliese
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| | - F Stramaglia
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy. .,Microscopy and Magnetism Group, Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - L Simonelli
- CELLS - ALBA Synchrotron Radiation Facility, Carrer de la Llum 2-26, 08290, Cerdanyola del Valles, Barcelona, Spain
| | - C Marini
- CELLS - ALBA Synchrotron Radiation Facility, Carrer de la Llum 2-26, 08290, Cerdanyola del Valles, Barcelona, Spain
| | - K Terashima
- Research Institute for Interdisciplinary Science (RIIS), Okayama University, Okayama 700-8530, Japan.,National Institute for Materials Science, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan
| | - T Wakita
- Research Institute for Interdisciplinary Science (RIIS), Okayama University, Okayama 700-8530, Japan
| | - S Ayukawa
- Research Institute for Interdisciplinary Science (RIIS), Okayama University, Okayama 700-8530, Japan
| | - T Yokoya
- Research Institute for Interdisciplinary Science (RIIS), Okayama University, Okayama 700-8530, Japan
| | - K Kudo
- Department of Physics, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - M Nohara
- Department of Quantum Matter, Hiroshima University, Hiroshima 739-8530, Japan
| | - T Mizokawa
- Department of Applied Physics, Waseda University, Tokyo 169-8555, Japan
| | - N L Saini
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| |
Collapse
|
24
|
Li Y, Shen D, Kreisel A, Chen C, Wei T, Xu X, Wang J. Anisotropic Gap Structure and Sign Reversal Symmetry in Monolayer Fe(Se,Te). NANO LETTERS 2023; 23:140-147. [PMID: 36450010 DOI: 10.1021/acs.nanolett.2c03735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The iron-based superconductors are an ideal platform to reveal the enigma of the unconventional superconductivity and potential topological superconductivity. Among them, the monolayer Fe(Se,Te)/SrTiO3(001), which is proposed to be topological nontrivial, shows interface-enhanced high-temperature superconductivity in the two-dimensional limit. However, the experimental studies on the superconducting pairing mechanism of monolayer Fe(Se,Te) films are still limited. Here, by measuring the quasiparticle interference in monolayer Fe(Se,Te)/SrTiO3(001), we report the observation of the anisotropic structure of the large superconducting gap and the sign change of the superconducting gap on different electron pockets. The results are well consistent with the "bonding-antibonding" s±-wave pairing symmetry driven by spin fluctuations in conjunction with spin-orbit coupling. Our work is of basic significance not only for a unified superconducting formalism in the iron-based superconductors, but also for understanding of topological superconductivity in high-temperature superconductors.
Collapse
Affiliation(s)
- Yu Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing100871, China
| | - Dingyu Shen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing100871, China
| | - Andreas Kreisel
- Institut für Theoretische Physik, Universität Leipzig, D-04103Leipzig, Germany
| | - Cheng Chen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing100871, China
| | - Tianheng Wei
- International Center for Quantum Materials, School of Physics, Peking University, Beijing100871, China
| | - Xiaotong Xu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing100871, China
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing100871, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing100190, China
- Beijing Academy of Quantum Information Sciences, Beijing100193, China
| |
Collapse
|
25
|
Hall Effect Anisotropy in the Paramagnetic Phase of Ho 0.8Lu 0.2B 12 Induced by Dynamic Charge Stripes. Molecules 2023; 28:molecules28020676. [PMID: 36677734 PMCID: PMC9863903 DOI: 10.3390/molecules28020676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/22/2022] [Accepted: 12/31/2022] [Indexed: 01/11/2023] Open
Abstract
A detailed study of charge transport in the paramagnetic phase of the cage-cluster dodecaboride Ho0.8Lu0.2B12 with an instability both of the fcc lattice (cooperative Jahn−Teller effect) and the electronic structure (dynamic charge stripes) was carried out at temperatures 1.9−300 K in magnetic fields up to 80 kOe. Four mono-domain single crystals of Ho0.8Lu0.2B12 samples with different crystal axis orientation were investigated in order to establish the singularities of Hall effect, which develop due to (i) the electronic phase separation (stripes) and (ii) formation of the disordered cage-glass state below T*~60 K. It was demonstrated that a considerable intrinsic anisotropic positive component ρanxy appears at low temperatures in addition to the ordinary negative Hall resistivity contribution in magnetic fields above 40 kOe applied along the [001] and [110] axes. A relation between anomalous components of the resistivity tensor ρanxy~ρanxx1.7 was found for H||[001] below T*~60 K, and a power law ρanxy~ρanxx0.83 for the orientation H||[110] at temperatures T < TS~15 K. It is argued that below characteristic temperature TS~15 K the anomalous odd ρanxy(T) and even ρanxx(T) parts of the resistivity tensor may be interpreted in terms of formation of long chains in the filamentary structure of fluctuating charges (stripes). We assume that these ρanxy(H||[001]) and ρanxy(H||[110]) components represent the intrinsic (Berry phase contribution) and extrinsic (skew scattering) mechanism, respectively. Apart from them, an additional ferromagnetic contribution to both isotropic and anisotropic components in the Hall signal was registered and attributed to the effect of magnetic polarization of 5d states (ferromagnetic nano-domains) in the conduction band of Ho0.8Lu0.2B12.
Collapse
|
26
|
Huan Y, Luo T, Han X, Ge J, Cui F, Zhu L, Hu J, Zheng F, Zhao X, Wang L, Wang J, Zhang Y. Composition-Controllable Syntheses and Property Modulations from 2D Ferromagnetic Fe 5 Se 8 to Metallic Fe 3 Se 4 Nanosheets. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2207276. [PMID: 36263871 DOI: 10.1002/adma.202207276] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/27/2022] [Indexed: 06/16/2023]
Abstract
Exploring new-type 2D magnetic materials with high magnetic transition temperature and robust air stability has attracted wide attention for developing innovative spintronic devices. Recently, intercalation of native metal atoms into the van der Waals gaps of 2D layered transition metal dichalcogenides (TMDs) has been developed to form 2D non-layered magnetic TMDs, while only succeeded in limited systems (e.g., Cr2 S3 , Cr5 Te8 ). Herein, composition-controllable syntheses of 2D non-layered iron selenide nanosheets (25% Fe-intercalated triclinic Fe5 Se8 and 50% Fe-intercalated monoclinic Fe3 Se4 ) are firstly reported, via a robust chemical vapor deposition strategy. Specifically, the 2D Fe5 Se8 exhibits intrinsic room-temperature ferromagnetic property, which is explained by the change of electron spin states from layered 1T'-FeSe2 to non-layered Fe-intercalated Fe5 Se8 based on density functional theory calculations. In contrast, the ultrathin Fe3 Se4 presents novel metallic features comparable with that of metallic TMDs. This work hereby sheds light on the composition-controllable synthesis and fundamental property exploration of 2D self-intercalation induced novel TMDs compounds, by propelling their application explorations in nanoelectronics and spintronics-related fields.
Collapse
Affiliation(s)
- Yahuan Huan
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Tiantian Luo
- Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Department of Physics, Jinan University, Guangzhou, 510632, P. R. China
| | - Xiaocang Han
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Jun Ge
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, P. R. China
| | - Fangfang Cui
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Lijie Zhu
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Jingyi Hu
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Feipeng Zheng
- Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Department of Physics, Jinan University, Guangzhou, 510632, P. R. China
| | - Xiaoxu Zhao
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, P. R. China
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, P. R. China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100871, P. R. China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100190, P. R. China
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, P. R. China
| | - Yanfeng Zhang
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| |
Collapse
|
27
|
Ru H, Li Z, Wang S, Xiang B, Wang Y. Suppression and Revival of Superconducting Phase Coherence in Monolayer FeSe/SrTiO 3. NANO LETTERS 2022; 22:9997-10002. [PMID: 36519788 DOI: 10.1021/acs.nanolett.2c03587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Monolayer FeSe grown on SrTiO3 (FeSe/STO) is an interfacial high-temperature superconductor distinctively different from bulk FeSe. However, the superconducting phase coherence of the interface is challenging to probe due to its fragility in the atmosphere. Here, we perform in situ mutual inductance under ultrahigh vacuum on FeSe/STO in combination with band mapping by angle-resolved photoemission spectroscopy. We find that even though the monolayer shows a gap-closing temperature above 50 K, no diamagnetism is visible down to 5 K. This is the case for few-layer FeSe/STO until it exceeds a critical number of five layers, where diamagnetism suddenly appears. The suppression of diamagnetism in the monolayer is also lifted by depositing a top FeTe layer. However, Tc and superfluid density both decrease with thicker FeTe, suggesting unconventional electron pairing and phase coherence competition. Our observation may be understood by a scenario in which the interfacial superconducting phase coherence is highly anisotropic.
Collapse
Affiliation(s)
- Hao Ru
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Zhijie Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Shiyuan Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Bingke Xiang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | - Yihua Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, People's Republic of China
| |
Collapse
|
28
|
Wang L, He W, Huang G, Xue H, Zhang G, Mu G, Wu S, An Z, Zheng C, Chen Y, Li W. Two-Dimensional Superconductivity at the Titanium Sesquioxide Heterointerface. ACS NANO 2022; 16:16150-16157. [PMID: 36121352 DOI: 10.1021/acsnano.2c04795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The study of exotic superconductivity in two dimensions has been a central theme in the solid state and materials research communities. Experimentally exploring and identifying exotic, fascinating interface superconductors with a high transition temperature (Tc) are challenging. Here, we report an experimental observation of intriguing two-dimensional superconductivity with a Tc of up to 3.8 K at the interface between a Mott insulator Ti2O3 and polar semiconductor GaN. At the verge of superconductivity, we also observe a striking quantum metallic-like state, demonstrating that it is a precursor to the two-dimensional superconductivity as the temperature is decreased. Our work shows an exciting opportunity to exploit the underlying, emergent quantum phenomena at the heterointerfaces via heterostructure engineering.
Collapse
Affiliation(s)
- Lijie Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Wenhao He
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Guangyi Huang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Huanyi Xue
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Guanqun Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Gang Mu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Shiwei Wu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Zhenghua An
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Changlin Zheng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yan Chen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Wei Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| |
Collapse
|
29
|
Stoichiometric Growth of Monolayer FeSe Superconducting Films Using a Selenium Cracking Source. CRYSTALS 2022. [DOI: 10.3390/cryst12060853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
As a novel interfacial high-temperature superconductor, monolayer FeSe on SrTiO3 has been intensely studied in the past decade. The high selenium flux involved in the traditional growth method complicates the film’s composition and entails more sample processing to realize the superconductivity. Here we use a Se cracking source for the molecular beam epitaxy growth of FeSe films to boost the reactivity of the Se flux. Reflection high-energy electron diffraction shows that the growth rate of FeSe increases with the increasing Se flux when the Fe flux is fixed, indicating that the Se over-flux induces Fe vacancies. Through careful tuning, we find that the proper Se/Fe flux ratio with Se cracked that is required for growing stoichiometric FeSe is close to 1, much lower than that with the uncracked Se flux. Furthermore, the FeSe film produced by the optimized conditions shows high-temperature superconductivity in the transport measurements without any post-growth treatment. Our work reinforces the importance of stoichiometry for superconductivity and establishes a simpler and more efficient approach to fabricating monolayer FeSe superconducting films.
Collapse
|
30
|
Liu C, Kreisel A, Zhong S, Li Y, Andersen BM, Hirschfeld P, Wang J. Orbital-Selective High-Temperature Cooper Pairing Developed in the Two-Dimensional Limit. NANO LETTERS 2022; 22:3245-3251. [PMID: 35416679 DOI: 10.1021/acs.nanolett.1c04863] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
For multiband superconductors, the orbital multiplicity yields orbital differentiation in normal-state properties and can lead to orbital-selective spin-fluctuation Cooper pairing. The orbital-selective phenomenon has become increasingly pivotal in clarifying the pairing "enigma", particularly for multiband high-temperature superconductors. Meanwhile, in one-unit-cell (1-UC) FeSe/SrTiO3, since the standard electron-hole Fermi pocket nesting scenario is inapplicable, the actual pairing mechanism is subject to intense debate. Here, by measuring high-resolution Bogoliubov quasiparticle interference, we report observations of highly anisotropic magnetic Cooper pairing in 1-UC FeSe. Theoretically, it is important to incorporate orbitally selective effects of electronic correlations within a spin-fluctuation pairing calculation, where the dxy orbital becomes coherence-suppressed. The resulting pairing gap is compatible with the experimental findings, which suggests that high-Tc Cooper pairing with orbital selectivity applies to 2D-limit 1-UC FeSe. Our findings imply the general existence of orbital selectivity in iron-based superconductors and the universal significance of electron correlations in high-Tc superconductors.
Collapse
Affiliation(s)
- Chaofei Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Andreas Kreisel
- Institut für Theoretische Physik, Universität Leipzig, D-04103 Leipzig, Germany
| | - Shan Zhong
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Yu Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Brian M Andersen
- Niels Bohr Institute, University of Copenhagen, Jagtvej 128, DK-2200 Copenhagen, Denmark
| | - Peter Hirschfeld
- Department of Physics, University of Florida, Gainesville, Florida 32611, United States
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, People's Republic of China
| |
Collapse
|
31
|
Bai Z, He D, Fu S, Miao Q, Liu S, Huang M, Zhao K, Wang Y, Zhang X. Recent progress in electron–phonon interaction of two‐dimensional materials. NANO SELECT 2022. [DOI: 10.1002/nano.202100367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Zhiying Bai
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Dawei He
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Shaohua Fu
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Qing Miao
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Shuangyan Liu
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Mohan Huang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Kun Zhao
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Yongsheng Wang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| | - Xiaoxian Zhang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China
| |
Collapse
|
32
|
Xu HS, Wu S, Zheng H, Yin R, Li Y, Wang X, Tang K. Research Progress of FeSe-based Superconductors Containing Ammonia/Organic Molecules Intercalation. Top Curr Chem (Cham) 2022; 380:11. [PMID: 35122164 DOI: 10.1007/s41061-022-00368-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 01/17/2022] [Indexed: 10/19/2022]
Abstract
As an important part of Fe-based superconductors, FeSe-based superconductors have become a hot field in condensed matter physics. The exploration and preparation of such superconducting materials form the basis of studying their physical properties. With the help of various alkali/alkaline-earth/rare-earth metals, different kinds of ammonia/organic molecules have been intercalated into the FeSe layer to form a large number of FeSe-based superconductors with diverse structures and different layer spacing. Metal cations can effectively provide carriers to the superconducting FeSe layer, thus significantly increasing the superconducting transition temperature. The orientation of organic molecules often plays an important role in structural modification and can be used to fine-tune superconductivity. This review introduces the crystal structures and superconducting properties of several typical FeSe-based superconductors containing ammonia/organic molecules intercalation discovered in recent years, and the effects of FeSe layer spacing and superconducting transition temperature are briefly summarized.
Collapse
Affiliation(s)
- Han-Shu Xu
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, 230026, People's Republic of China.
| | - Shusheng Wu
- Department of Chemistry, University of Science and Technology of China, Hefei, 230026, People's Republic of China
| | - Hui Zheng
- Department of Chemistry, University of Science and Technology of China, Hefei, 230026, People's Republic of China
| | - Ruotong Yin
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, 230026, People's Republic of China
| | - Yuanji Li
- Department of Physics, University of Science and Technology of China, Hefei, 230026, People's Republic of China
| | - Xiaoxiong Wang
- College of Physics Science, Qingdao University, Qingdao, 266071, People's Republic of China.
| | - Kaibin Tang
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, 230026, People's Republic of China. .,Department of Chemistry, University of Science and Technology of China, Hefei, 230026, People's Republic of China.
| |
Collapse
|
33
|
Iron pnictides and chalcogenides: a new paradigm for superconductivity. Nature 2022; 601:35-44. [PMID: 34987212 DOI: 10.1038/s41586-021-04073-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 09/29/2021] [Indexed: 11/09/2022]
Abstract
Superconductivity is a remarkably widespread phenomenon that is observed in most metals cooled to very low temperatures. The ubiquity of such conventional superconductors, and the wide range of associated critical temperatures, is readily understood in terms of the well-known Bardeen-Cooper-Schrieffer theory. Occasionally, however, unconventional superconductors are found, such as the iron-based materials, which extend and defy this understanding in unexpected ways. In the case of the iron-based superconductors, this includes the different ways in which the presence of multiple atomic orbitals can manifest in unconventional superconductivity, giving rise to a rich landscape of gap structures that share the same dominant pairing mechanism. In addition, these materials have also led to insights into the unusual metallic state governed by the Hund's interaction, the control and mechanisms of electronic nematicity, the impact of magnetic fluctuations and quantum criticality, and the importance of topology in correlated states. Over the fourteen years since their discovery, iron-based superconductors have proven to be a testing ground for the development of novel experimental tools and theoretical approaches, both of which have extensively influenced the wider field of quantum materials.
Collapse
|
34
|
Cheng M, Zhao X, Zeng Y, Wang P, Wang Y, Wang T, Pennycook SJ, He J, Shi J. Phase-Tunable Synthesis and Etching-Free Transfer of Two-Dimensional Magnetic FeTe. ACS NANO 2021; 15:19089-19097. [PMID: 34697943 DOI: 10.1021/acsnano.1c05738] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two-dimensional (2D) Fe-chalcogenides (e.g., FeS, FeSe, and FeTe, etc.) have sparked extensive interest due to their rich phase diagrams including superconductivity, magnetism, and topological state, as well as versatile applications in electronic devices and energy related fields. However, the phase-tunable synthesis and green transfer of such fascinating materials still remain challenging. Herein, we develop a temperature-mediated chemical vapor deposition (CVD) approach to grow ultrathin nonlayered hexagonal and layered tetragonal FeTe nanosheets on mica substrates, with their thicknesses down to ∼2.3 and ∼4.0 nm, respectively. Interestingly, we have observed exciting ferromagnetism with the Curie temperature approaching ∼300 K and high conductivity (∼1.96 × 105 S m-1) in 2D hexagonal FeTe. More significantly, we have designed a swift, high-efficiency, and etching-free method for the transfer of 2D FeTe nanosheets onto arbitrary substrates, and such a transfer strategy enables the cyclic utilization of growth substrates. These results should propel the further development of phase-tunable synthesis and green transfer of 2D Fe-chalcogenides, as well as their potential applications in spintronic devices.
Collapse
Affiliation(s)
- Mo Cheng
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Xiaoxu Zhao
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Yan Zeng
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Peng Wang
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Yuzhu Wang
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Ti Wang
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Stephen John Pennycook
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jun He
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jianping Shi
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| |
Collapse
|
35
|
Yu T, Wright J, Khalsa G, Pamuk B, Chang CS, Matveyev Y, Wang X, Schmitt T, Feng D, Muller DA, Xing HG, Jena D, Strocov VN. Momentum-resolved electronic structure and band offsets in an epitaxial NbN/GaN superconductor/semiconductor heterojunction. SCIENCE ADVANCES 2021; 7:eabi5833. [PMID: 34936435 PMCID: PMC8694612 DOI: 10.1126/sciadv.abi5833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 11/05/2021] [Indexed: 06/14/2023]
Abstract
The electronic structure of heterointerfaces is a pivotal factor for their device functionality. We use soft x-ray angle-resolved photoelectron spectroscopy to directly measure the momentum-resolved electronic band structures on both sides of the Schottky heterointerface formed by epitaxial films of the superconducting NbN on semiconducting GaN, and determine their momentum-dependent interfacial band offset as well as the band-bending profile. We find, in particular, that the Fermi states in NbN are well separated in energy and momentum from the states in GaN, excluding any notable electronic cross-talk of the superconducting states in NbN to GaN. We support the experimental findings with first-principles calculations for bulk NbN and GaN. The Schottky barrier height obtained from photoemission is corroborated by electronic transport and optical measurements. The momentum-resolved understanding of electronic properties of interfaces elucidated in our work opens up new frontiers for the quantum materials where interfacial states play a defining role.
Collapse
Affiliation(s)
- Tianlun Yu
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - John Wright
- Materials Science and Engineering, Cornell University, Ithaca, NY 14850, USA
| | - Guru Khalsa
- Materials Science and Engineering, Cornell University, Ithaca, NY 14850, USA
| | - Betül Pamuk
- Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM), Cornell University, Ithaca, NY 14853, USA
| | - Celesta S. Chang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
| | - Yury Matveyev
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Xiaoqiang Wang
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Thorsten Schmitt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Donglai Feng
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
- Hefei National Laboratory for Physical Science at Microscale, CAS Center for Excellence in Quantum Information and Quantum Physics, and Department of Physics, University of Science and Technology of China, Hefei 230026, China
| | - David A. Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA
| | - Huili Grace Xing
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA
- Electrical and Computer Engineering and Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Debdeep Jena
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA
- Electrical and Computer Engineering and Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Vladimir N. Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| |
Collapse
|
36
|
Cai X, Li ZX, Yao H. Antiferromagnetism Induced by Bond Su-Schrieffer-Heeger Electron-Phonon Coupling: A Quantum Monte Carlo Study. PHYSICAL REVIEW LETTERS 2021; 127:247203. [PMID: 34951814 DOI: 10.1103/physrevlett.127.247203] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/22/2021] [Accepted: 10/28/2021] [Indexed: 06/14/2023]
Abstract
Antiferromagnetism (AFM) such as Néel ordering is often closely related to Coulomb interactions such as Hubbard repulsion in two-dimensional (2D) systems. Whether Néel AFM ordering in two dimensions can be dominantly induced by electron-phonon couplings (EPC) has not been completely understood. Here, by employing numerically exact sign-problem-free quantum Monte Carlo (QMC) simulations, we show that bond Su-Schrieffer-Heeger (SSH) phonons with frequency ω and EPC constant λ can induce AFM ordering for a wide range of phonon frequency ω>ω_{c}. For ω<ω_{c}, a valence-bond-solid (VBS) order appears and there is a direct quantum phase transition between VBS and AFM phases at ω_{c}. The phonon mechanism of the AFM ordering is related to the fact that SSH phonons directly couple to electron hopping whose second-order process can induce an effective AFM spin exchange. Our results shall shed new light on understanding AFM ordering in correlated quantum materials.
Collapse
Affiliation(s)
- Xun Cai
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
| | - Zi-Xiang Li
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Hong Yao
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
| |
Collapse
|
37
|
Kimura M, He X, Katase T, Tadano T, Tomczak JM, Minohara M, Aso R, Yoshida H, Ide K, Ueda S, Hiramatsu H, Kumigashira H, Hosono H, Kamiya T. Large phonon drag thermopower boosted by massive electrons and phonon leaking in LaAlO 3/LaNiO 3/LaAlO 3 heterostructure. NANO LETTERS 2021; 21:9240-9246. [PMID: 34709840 PMCID: PMC8587880 DOI: 10.1021/acs.nanolett.1c03143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/11/2021] [Indexed: 06/04/2023]
Abstract
An unusually large thermopower (S) enhancement is induced by heterostructuring thin films of the strongly correlated electron oxide LaNiO3. The phonon-drag effect, which is not observed in bulk LaNiO3, enhances S for thin films compressively strained by LaAlO3 substrates. By a reduction in the layer thickness down to three unit cells and subsequent LaAlO3 surface termination, a 10 times S enhancement over the bulk value is observed due to large phonon drag S (Sg), and the Sg contribution to the total S occurs over a much wider temperature range up to 220 K. The Sg enhancement originates from the coupling of lattice vibration to the d electrons with large effective mass in the compressively strained ultrathin LaNiO3, and the electron-phonon interaction is largely enhanced by the phonon leakage from the LaAlO3 substrate and the capping layer. The transition-metal oxide heterostructures emerge as a new playground to manipulate electronic and phononic properties in the quest for high-performance thermoelectrics.
Collapse
Affiliation(s)
- Masatoshi Kimura
- Laboratory
for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
| | - Xinyi He
- Laboratory
for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
| | - Takayoshi Katase
- Laboratory
for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
- PRESTO,
Japan Science and Technology Agency, 7 Gobancho, Chiyoda, Tokyo 102-0076, Japan
| | - Terumasa Tadano
- National
Institute for Materials Science, Sengen, Tsukuba 305-0047, Japan
| | - Jan M. Tomczak
- Institute
of Solid State Physics, Vienna University
of Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna, Austria
| | - Makoto Minohara
- Research
Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Ryotaro Aso
- Department
of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka, Fukuoka 819-0395, Japan
| | - Hideto Yoshida
- The
Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Keisuke Ide
- Laboratory
for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
| | - Shigenori Ueda
- Research
Center for Functional Materials, National
Institute for Materials Science, Namiki, Tsukuba 305-0044, Japan
- Research
Center for Advanced Measurement and Characterization, National Institute for Materials Science, Tsukuba 305-0047, Japan
- Synchrotron
X-ray Station at SPring-8, National Institute
for Materials Science, 1-1-1 Sayo, Hyogo, 679-5148, Japan
| | - Hidenori Hiramatsu
- Laboratory
for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
- Materials
Research Center for Element Strategy, Tokyo
Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
| | - Hiroshi Kumigashira
- Photon
Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan
- Institute
of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Hideo Hosono
- Materials
Research Center for Element Strategy, Tokyo
Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
| | - Toshio Kamiya
- Laboratory
for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
- Materials
Research Center for Element Strategy, Tokyo
Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
| |
Collapse
|
38
|
Obata Y, Sato M, Kondo Y, Yamaguchi Y, Karateev IA, Pavlov I, Vasiliev AL, Haindl S. Chemical Composition Control at the Substrate Interface as the Key for FeSe Thin-Film Growth. ACS APPLIED MATERIALS & INTERFACES 2021; 13:53162-53170. [PMID: 34698487 DOI: 10.1021/acsami.1c14451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The strong fascination exerted by the binary compound of FeSe demands reliable engineering protocols and more effective approaches toward inducing superconductivity in FeSe thin films. Our study addresses the peculiarities in pulsed laser deposition that determine FeSe thin-film growth and focuses on the film/substrate interface, which has only been considered hypothetically in the past literature. The FeSe/MgO interface has been assumed (1) to be clean and (2) to obey lattice-matching epitaxy. Our studies reveal that both assumptions are misleading and demonstrate the tendency for domain-matching epitaxial growth, which accompanies the problem of chemical heterogeneity. We propose that homogenization of the film/substrate interface by an Fe buffer can improve the control of stoichiometry and nanostrain in a way that favors superconductivity even in ultrathin FeSe films. We will also show that on a chemically homogenized FeSe/Fe interface, the control of film texture with preparation conditions is still possible.
Collapse
Affiliation(s)
- Yukiko Obata
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Michiko Sato
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Yuji Kondo
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Yuta Yamaguchi
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Igor A Karateev
- National Research Centre ″Kurchatov Institute,″ pl. Akademika Kurchatova 1, Moscow 123182, Russian Federation
| | - Ivan Pavlov
- Shubnikov Institute of Crystallography of FSRC "Crystallography and Photonics" Russian Academy of Sciences, Leninsky pr. 59, Moscow 119333, Russian Federation
| | - Alexander L Vasiliev
- National Research Centre ″Kurchatov Institute,″ pl. Akademika Kurchatova 1, Moscow 123182, Russian Federation
- Shubnikov Institute of Crystallography of FSRC "Crystallography and Photonics" Russian Academy of Sciences, Leninsky pr. 59, Moscow 119333, Russian Federation
- Moscow Institute of Physics and Technology, National Research University, Dolgoprudny, Moscow region 141701, Russian Federation
| | - Silvia Haindl
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| |
Collapse
|
39
|
Wang Y, Chen Z, Shi T, Moritz B, Shen ZX, Devereaux TP. Phonon-Mediated Long-Range Attractive Interaction in One-Dimensional Cuprates. PHYSICAL REVIEW LETTERS 2021; 127:197003. [PMID: 34797146 DOI: 10.1103/physrevlett.127.197003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/22/2021] [Indexed: 06/13/2023]
Abstract
Establishing a minimal microscopic model for cuprates is a key step towards the elucidation of a high-T_{c} mechanism. By a quantitative comparison with a recent in situ angle-resolved photoemission spectroscopy measurement in doped 1D cuprate chains, our simulation identifies a crucial contribution from long-range electron-phonon coupling beyond standard Hubbard models. Using reasonable ranges of coupling strengths and phonon energies, we obtain a strong attractive interaction between neighboring electrons, whose strength is comparable to experimental observations. Nonlocal couplings play a significant role in the mediation of neighboring interactions. Considering the structural and chemical similarity between 1D and 2D cuprate materials, this minimal model with long-range electron-phonon coupling will provide important new insights on cuprate high-T_{c} superconductivity and related quantum phases.
Collapse
Affiliation(s)
- Yao Wang
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29631, USA
| | - Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Tao Shi
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Brian Moritz
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Zhi-Xun Shen
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Thomas P Devereaux
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| |
Collapse
|
40
|
Yan C, Green E, Fukumori R, Protic N, Lee SH, Fernandez-Mulligan S, Raja R, Erdakos R, Mao Z, Yang S. An integrated quantum material testbed with multi-resolution photoemission spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:113907. [PMID: 34852521 DOI: 10.1063/5.0072979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 10/30/2021] [Indexed: 06/13/2023]
Abstract
We present the development of a multi-resolution photoemission spectroscopy (MRPES) setup, which probes quantum materials in energy, momentum, space, and time. This versatile setup integrates three light sources in one photoemission setup and can conveniently switch between traditional angle-resolved photoemission spectroscopy (ARPES), time-resolved ARPES (trARPES), and micrometer-scale spatially resolved ARPES. It provides a first-time all-in-one solution to achieve an energy resolution of <4 meV, a time resolution of <35 fs, and a spatial resolution of ∼10 μm in photoemission spectroscopy. Remarkably, we obtain the shortest time resolution among the trARPES setups using solid-state nonlinear crystals for frequency upconversion. Furthermore, this MRPES setup is integrated with a shadow-mask assisted molecular beam epitaxy system, which transforms the traditional photoemission spectroscopy into a quantum device characterization instrument. We demonstrate the functionalities of this novel quantum material testbed using FeSe/SrTiO3 thin films and MnBi4Te7 magnetic topological insulators.
Collapse
Affiliation(s)
- Chenhui Yan
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Emanuel Green
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Riku Fukumori
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Nikola Protic
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Seng Huat Lee
- Department of Physics, Pennsylvania State University, University Park, State College, Pennslyvania, 16802, USA
| | | | - Rahim Raja
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Robin Erdakos
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Zhiqiang Mao
- Department of Physics, Pennsylvania State University, University Park, State College, Pennslyvania, 16802, USA
| | - Shuolong Yang
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| |
Collapse
|
41
|
Song Y, Chen Z, Zhang Q, Xu H, Lou X, Chen X, Xu X, Zhu X, Tao R, Yu T, Ru H, Wang Y, Zhang T, Guo J, Gu L, Xie Y, Peng R, Feng D. High temperature superconductivity at FeSe/LaFeO 3 interface. Nat Commun 2021; 12:5926. [PMID: 34635672 PMCID: PMC8505662 DOI: 10.1038/s41467-021-26201-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 09/15/2021] [Indexed: 11/09/2022] Open
Abstract
Enormous enhancement of superconducting pairing temperature (Tg) to 65 K in FeSe/SrTiO3 has made it a spotlight. Despite the effort of interfacial engineering, FeSe interfaced with TiOx remains the unique case in hosting high Tg, hindering a decisive understanding on the general mechanism and ways to further improving Tg. Here we constructed a new high-Tg interface, single-layer FeSe interfaced with FeOx-terminated LaFeO3. Large superconducting gap and diamagnetic response evidence that the superconducting pairing can emerge near 80 K, highest amongst all-known interfacial superconductors. Combining various techniques, we reveal interfacial charge transfer and strong interfacial electron-phonon coupling (EPC) in FeSe/LaFeO3, showing that the cooperative pairing mechanism works beyond FeSe-TiOx. Intriguingly, the stronger interfacial EPC than that in FeSe/SrTiO3 is likely induced by the stronger interfacial bonding in FeSe/LaFeO3, and can explain the higher Tg according to recent theoretical calculations, pointing out a workable route in designing new interfaces to achieve higher Tg.
Collapse
Affiliation(s)
- Yuanhe Song
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
| | - Zheng Chen
- Department of Physics, Zhejiang University, 310027, Hangzhou, China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
| | - Haichao Xu
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
- Shanghai Research Center for Quantum Sciences, 201315, Shanghai, China
| | - Xia Lou
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
| | - Xiaoyang Chen
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
| | - Xiaofeng Xu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
| | - Xuetao Zhu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
| | - Ran Tao
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
| | - Tianlun Yu
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
| | - Hao Ru
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
| | - Yihua Wang
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
- Shanghai Research Center for Quantum Sciences, 201315, Shanghai, China
| | - Tong Zhang
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China
- Shanghai Research Center for Quantum Sciences, 201315, Shanghai, China
| | - Jiandong Guo
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China.
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China.
| | - Yanwu Xie
- Department of Physics, Zhejiang University, 310027, Hangzhou, China.
| | - Rui Peng
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, 200438, Shanghai, China.
- Shanghai Research Center for Quantum Sciences, 201315, Shanghai, China.
| | - Donglai Feng
- Shanghai Research Center for Quantum Sciences, 201315, Shanghai, China.
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, 230026, Hefei, Anhui, China.
- Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, China.
| |
Collapse
|
42
|
Obata Y, Karateev IA, Pavlov I, Vasiliev AL, Haindl S. Challenges for Pulsed Laser Deposition of FeSe Thin Films. MICROMACHINES 2021; 12:1224. [PMID: 34683275 PMCID: PMC8540977 DOI: 10.3390/mi12101224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/28/2021] [Accepted: 10/05/2021] [Indexed: 11/16/2022]
Abstract
Anti-PbO-type FeSe shows an advantageous dependence of its superconducting properties with mechanical strain, which could be utilized as future sensor functionality. Although superconducting FeSe thin films can be grown by various methods, ultrathin films needed in potential sensor applications were only achieved on a few occasions. In pulsed laser deposition, the main challenges can be attributed to such factors as controlling film stoichiometry (i.e., volatile elements during the growth), nucleation, and bonding to the substrate (i.e., film/substrate interface control) and preventing the deterioration of superconducting properties (i.e., by surface oxidization). In the present study, we address various technical issues in thin film growth of FeSe by pulsed laser deposition, which pose constraints in engineering and reduce the application potential for FeSe thin films in sensor devices. The results indicate the need for sophisticated engineering protocols that include interface control and surface protection from chemical deterioration. This work provides important actual limitations for pulsed laser deposition (PLD) of FeSe thin films with the thicknesses below 30 nm.
Collapse
Affiliation(s)
- Yukiko Obata
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Igor A. Karateev
- National Research Centre “Kurchatov Institute”, pl. Akademika Kurchatova 1, 123182 Moscow, Russia;
| | - Ivan Pavlov
- Shubnikov Institute of Crystallography of FSRC “Crystallography and Photonics” Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow, Russia;
| | - Alexander L. Vasiliev
- National Research Centre “Kurchatov Institute”, pl. Akademika Kurchatova 1, 123182 Moscow, Russia;
- Shubnikov Institute of Crystallography of FSRC “Crystallography and Photonics” Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow, Russia;
- Moscow Institute of Physics and Technology, National Research University, Dolgoprudny, 141701 Moscow, Russia
| | - Silvia Haindl
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| |
Collapse
|
43
|
Abstract
ConspectusQuantum materials refers to a class of materials with exotic properties that arise from the quantum mechanical nature of their constituent electrons, exhibiting, for example, high-temperature superconductivity, colossal magnetoresistivity, multiferroicity, and topological behavior. Quantum materials often have incompletely filled d- or f-electron shells with narrow energy bands, and the conduct of their electrons is strongly correlated. One distinct characteristic of the materials is that their electronic states are often spatially inhomogeneous and thus well suited for study using a spatially resolved electron beam with its great scattering power and sensitivity to atomic ionicity. Furthermore, most of these exotic properties only manifest at very low temperatures, posing a challenge to modern electron microscopy. It requires extraordinarily instrument stabilities at cryogenic temperatures with critical spatial, temporal, and energy resolutions in both static and dynamic manner to probe these materials. On the other hand, the ability to directly visualize the atomic, electronic and spin structures and inhomogeneities of quantum materials and correlate them to their functionalities creates enormous opportunities. At the most elementary levels of condensed matter physics, understanding the competing order of electron, spin, orbital, and lattice and their degrees of freedom, the impacts of defects and interfaces, and the site-specific quantum phenomena and phase transitions that give rise to the emergent behaviors allows us to discover and control novel materials for quantum information science and technologies.In this Account, several of our research examples are selected to highlight the use of cryogenic electron microscopy (cryo-EM) to study strongly correlated quantum materials. We focus on the critical roles of heterogeneity, interfaces, defects, and disorder in crystal structure, magnetic structure, and electronic structure to understand the physical properties of the materials that cryo-EM enables. We show how electron crystallography coupled with Bragg diffraction and diffuse scattering analysis empowers us to reveal the nature of structural modulations, lattice distortion, and phonons and how quantitative electron diffraction can be used to map the distributions of the valence electrons that bond atoms together. We exploit transformative advances in imaging capabilities including the use of femtosecond laser and ultrafast electron diffraction to probe electron-lattice interactions and photoinduced transitions beyond equilibrium of matter. We review our Lorentz phase microscopy studies to illustrate the intriguing transformations among various topological chiral spin states under applied magnetic field at various cryogenic temperatures. Finally, we show that atomically resolved imaging and electron energy-loss spectroscopy at 10 K can be used to understand interface-enhanced superconductivity. The wide range of research and progress on quantum materials at low temperature reported here may inspire and attract more researchers in this ever-expanding field of cryo-EM.
Collapse
Affiliation(s)
- Yimei Zhu
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory Upton, New York 11973, United States
| |
Collapse
|
44
|
Bie YQ, Zong A, Wang X, Jarillo-Herrero P, Gedik N. A versatile sample fabrication method for ultrafast electron diffraction. Ultramicroscopy 2021; 230:113389. [PMID: 34530284 DOI: 10.1016/j.ultramic.2021.113389] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/21/2021] [Accepted: 08/30/2021] [Indexed: 11/16/2022]
Abstract
Integral to the exploration of nonequilibrium phenomena in solid-state systems is the study of lattice motion after photoexcitation by a femtosecond laser pulse. For the past two decades, ultrafast electron diffraction (UED) has played a critical role in this regard. Despite remarkable progress in instrumental development, this technique is still bottlenecked by a demanding sample preparation process, where ultrathin single crystals of large lateral size are typically required. In this work, we describe an efficient, versatile method that yields high-quality, laterally extended (≥ 100 µm), and thin (≤ 50 nm) single crystals on amorphous films of Si3N4 windows. It applies to most exfoliable materials, including those reactive in ambient conditions, and promises clean, flat surfaces. Besides the natural extension to fabricating van der Waals heterostructures, our method can also be applied to future-generation UED that enables additional control of sample parameters, such as electrostatic gating and excitation by a locally enhanced terahertz field. Our work significantly expands the type of samples for UED studies and also finds application in other time-resolved techniques such as attosecond extreme-ultraviolet absorption spectroscopy. This method hence provides further opportunities to explore photoinduced transitions and to discover novel states of matter out of equilibrium.
Collapse
Affiliation(s)
- Ya-Qing Bie
- State Key Lab of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou, 510275, China; Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02139, United States
| | - Alfred Zong
- Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02139, United States; University of California at Berkeley, Department of Chemistry, Berkeley, CA 94720, United States
| | - Xirui Wang
- Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02139, United States
| | - Pablo Jarillo-Herrero
- Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02139, United States
| | - Nuh Gedik
- Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02139, United States.
| |
Collapse
|
45
|
Gao J, Ding W, Zhang S, Zhang Z, Cui P. Coexistence of Superconductivity and Nontrivial Band Topology in Monolayered Cobalt Pnictides on SrTiO 3. NANO LETTERS 2021; 21:7396-7404. [PMID: 34431678 DOI: 10.1021/acs.nanolett.1c02830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
As an intrinsically layered material, FeSe has been extensively explored for potentially revealing the underlying mechanisms of high transition temperature (high-Tc) superconductivity and realizing topological superconductivity and Majorana zero modes. Here we use first-principles approaches to identify that the cobalt pnictides of CoX (X = As, Sb, Bi), none of which is a layered material in bulk form. Nevertheless, all can be stabilized as monolayered systems either in freestanding form or supported on the SrTiO3(001) substrate. We further show that each of the cobalt pnictides may potentially harbor high-Tc superconductivity beyond the Cu- and Fe-based superconducting families, and the underlying mechanism is inherently tied to their isovalency nature with the FeSe monolayer. Most strikingly, each of the monolayered CoX's on SrTiO3 is shown to be topologically nontrivial, and our findings provide promising new platforms for realizing topological superconductors in the two-dimensional limit.
Collapse
Affiliation(s)
- Jiaqing Gao
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wenjun Ding
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shunhong Zhang
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhenyu Zhang
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ping Cui
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| |
Collapse
|
46
|
Ren W, Ru H, Peng K, Li H, Lu S, Chen A, Wang P, Fang X, Li Z, Huang R, Wang L, Wang Y, Li F. Oxygen Adsorption Induced Superconductivity in Ultrathin FeTe Film on SrTiO 3(001). MATERIALS (BASEL, SWITZERLAND) 2021; 14:4584. [PMID: 34443107 PMCID: PMC8398274 DOI: 10.3390/ma14164584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/03/2021] [Accepted: 08/10/2021] [Indexed: 11/17/2022]
Abstract
The phenomenon of oxygen incorporation-induced superconductivity in iron telluride (Fe1+yTe, with antiferromagnetic (AFM) orders) is intriguing and quite different from the case of FeSe. Until now, the microscopic origin of the induced superconductivity and the role of oxygen are far from clear. Here, by combining in situ scanning tunneling microscopy/spectroscopy (STM/STS) and X-ray photoemission spectroscopy (XPS) on oxygenated FeTe, we found physically adsorbed O2 molecules crystallized into c (2/3 × 2) structure as an oxygen overlayer at low temperature, which was vital for superconductivity. The O2 overlayer were not epitaxial on the FeTe lattice, which implied weak O2 -FeTe interaction but strong molecular interactions. The energy shift observed in the STS and XPS measurements indicated a hole doping effect from the O2 overlayer to the FeTe layer, leading to a superconducting gap of 4.5 meV opened across the Fermi level. Our direct microscopic probe clarified the role of oxygen on FeTe and emphasized the importance of charge transfer effect to induce superconductivity in iron-chalcogenide thin films.
Collapse
Affiliation(s)
- Wei Ren
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, China;
| | - Hao Ru
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200438, China;
| | - Kun Peng
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China; (K.P.); (H.L.); (S.L.); (A.C.); (P.W.); (X.F.); (Z.L.); (R.H.)
| | - Huifang Li
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China; (K.P.); (H.L.); (S.L.); (A.C.); (P.W.); (X.F.); (Z.L.); (R.H.)
| | - Shuai Lu
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China; (K.P.); (H.L.); (S.L.); (A.C.); (P.W.); (X.F.); (Z.L.); (R.H.)
| | - Aixi Chen
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China; (K.P.); (H.L.); (S.L.); (A.C.); (P.W.); (X.F.); (Z.L.); (R.H.)
| | - Pengdong Wang
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China; (K.P.); (H.L.); (S.L.); (A.C.); (P.W.); (X.F.); (Z.L.); (R.H.)
| | - Xinwei Fang
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China; (K.P.); (H.L.); (S.L.); (A.C.); (P.W.); (X.F.); (Z.L.); (R.H.)
| | - Zhiyun Li
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China; (K.P.); (H.L.); (S.L.); (A.C.); (P.W.); (X.F.); (Z.L.); (R.H.)
| | - Rong Huang
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China; (K.P.); (H.L.); (S.L.); (A.C.); (P.W.); (X.F.); (Z.L.); (R.H.)
| | - Li Wang
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China; (K.P.); (H.L.); (S.L.); (A.C.); (P.W.); (X.F.); (Z.L.); (R.H.)
| | - Yihua Wang
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200438, China;
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Fangsen Li
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, China;
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences (CAS), Suzhou 215123, China; (K.P.); (H.L.); (S.L.); (A.C.); (P.W.); (X.F.); (Z.L.); (R.H.)
| |
Collapse
|
47
|
High-order replica bands in monolayer FeSe/SrTiO 3 revealed by polarization-dependent photoemission spectroscopy. Nat Commun 2021; 12:4573. [PMID: 34321473 PMCID: PMC8319137 DOI: 10.1038/s41467-021-24783-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 07/09/2021] [Indexed: 11/13/2022] Open
Abstract
The mechanism of the enhanced superconductivity in monolayer FeSe/SrTiO3 has been enthusiastically studied and debated over the past decade. One specific observation has been taken to be of central importance: the replica bands in the photoemission spectrum. Although suggestive of electron-phonon interaction in the material, the essence of these spectroscopic features remains highly controversial. In this work, we conduct angle-resolved photoemission spectroscopy measurements on monolayer FeSe/SrTiO3 using linearly polarized photons. This configuration enables unambiguous characterization of the valence electronic structure with a suppression of the spectral background. We consistently observe high-order replica bands derived from various Fe 3d bands, similar to those observed on bare SrTiO3. The intensity of the replica bands is unexpectedly high and different between dxy and dyz bands. Our results provide new insights on the electronic structure of this high-temperature superconductor and the physical origin of the photoemission replica bands. The origin of the photoemission replica bands in monolayer FeSe/SrTiO3 remains controversial. Here, the authors perform angle-resolved photoemission spectroscopy with polarized photon on FeSe/SrTiO3 and observe high-order replica bands with high intensity from various Fe 3d bands, suggesting a mixed mechanism.
Collapse
|
48
|
Faeth BD, Xie S, Yang S, Kawasaki JK, Nelson JN, Zhang S, Parzyck C, Mishra P, Li C, Jozwiak C, Bostwick A, Rotenberg E, Schlom DG, Shen KM. Interfacial Electron-Phonon Coupling Constants Extracted from Intrinsic Replica Bands in Monolayer FeSe/SrTiO_{3}. PHYSICAL REVIEW LETTERS 2021; 127:016803. [PMID: 34270322 DOI: 10.1103/physrevlett.127.016803] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/26/2021] [Accepted: 05/19/2021] [Indexed: 06/13/2023]
Abstract
The observation of replica bands by angle-resolved photoemission spectroscopy has ignited interest in the study of electron-phonon coupling at low carrier densities, particularly in monolayer FeSe/SrTiO_{3}, where the appearance of replica bands has motivated theoretical work suggesting that the interfacial coupling of electrons in the FeSe layer to optical phonons in the SrTiO_{3} substrate might contribute to the enhanced superconducting pairing temperature. Alternatively, it has also been recently proposed that such replica bands might instead originate from extrinsic final state losses associated with the photoemission process. Here, we perform a quantitative examination of replica bands in monolayer FeSe/SrTiO_{3}, where we are able to conclusively demonstrate that the replica bands are indeed signatures of intrinsic electron-boson coupling, and not associated with final state effects. A detailed analysis of the energy splittings and relative peak intensities between the higher-order replicas, as well as other self-energy effects, allows us to determine that the interfacial electron-phonon coupling in the system corresponds to a value of λ=0.19±0.02, providing valuable insights into the enhancement of superconductivity in monolayer FeSe/SrTiO_{3}. The methodology employed here can also serve as a new and general approach for making more rigorous and quantitative comparisons to theoretical calculations of electron-phonon interactions and coupling constants.
Collapse
Affiliation(s)
- Brendan D Faeth
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - Saien Xie
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - Shuolong Yang
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Jason K Kawasaki
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| | - Jocienne N Nelson
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - Shuyuan Zhang
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - Christopher Parzyck
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - Pramita Mishra
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - Chen Li
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - Christopher Jozwiak
- Advanced Light Source, E.O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Aaron Bostwick
- Advanced Light Source, E.O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Eli Rotenberg
- Advanced Light Source, E.O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Darrell G Schlom
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Kyle M Shen
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| |
Collapse
|
49
|
Naritsuka M, Terashima T, Matsuda Y. Controlling unconventional superconductivity in artificially engineered f-electron Kondo superlattices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:273001. [PMID: 33946054 DOI: 10.1088/1361-648x/abfdf2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 05/04/2021] [Indexed: 06/12/2023]
Abstract
Unconventional superconductivity and magnetism are intertwined on a microscopic level in a wide class of materials, including high-Tccuprates, iron pnictides, and heavy-fermion compounds. Interactions between superconducting electrons and bosonic fluctuations at the interface between adjacent layers in heterostructures provide a new approach to this most fundamental and hotly debated subject. We have been able to use a recent state-of-the-art molecular-beam-epitaxy technique to fabricate superlattices consisting of different heavy-fermion compounds with atomic thickness. These Kondo superlattices provide a unique opportunity to study the mutual interaction between unconventional superconductivity and magnetic order through the atomic interface. Here, we design and fabricate hybrid Kondo superlattices consisting of alternating layers of superconducting CeCoIn5withd-wave pairing symmetry and nonmagnetic metal YbCoIn5or antiferromagnetic heavy fermion metals such as CeRhIn5and CeIn3. In these Kondo superlattices, superconducting heavy electrons are confined within the two-dimensional CeCoIn5block layers and interact with neighboring nonmagnetic or magnetic layers through the interface. Superconductivity is strongly influenced by local inversion symmetry breaking at the interface in CeCoIn5/YbCoIn5superlattices. The superconducting and antiferromagnetic states coexist in spatially separated layers in CeCoIn5/CeRhIn5and CeCoIn5/CeIn3superlattices, but their mutual coupling via the interface significantly modifies the superconducting and magnetic properties. The fabrication of a wide variety of hybrid superlattices paves a new way to study the relationship between unconventional superconductivity and magnetism in strongly correlated materials.
Collapse
Affiliation(s)
- M Naritsuka
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - T Terashima
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| |
Collapse
|
50
|
Evolution of spin excitations from bulk to monolayer FeSe. Nat Commun 2021; 12:3122. [PMID: 34035254 PMCID: PMC8149670 DOI: 10.1038/s41467-021-23317-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 04/16/2021] [Indexed: 11/24/2022] Open
Abstract
In ultrathin films of FeSe grown on SrTiO3 (FeSe/STO), the superconducting transition temperature Tc is increased by almost an order of magnitude, raising questions on the pairing mechanism. As in other superconductors, antiferromagnetic spin fluctuations have been proposed to mediate SC making it essential to study the evolution of the spin dynamics of FeSe from the bulk to the ultrathin limit. Here, we investigate the spin excitations in bulk and monolayer FeSe/STO using resonant inelastic x-ray scattering (RIXS) and quantum Monte Carlo (QMC) calculations. Despite the absence of long-range magnetic order, bulk FeSe displays dispersive magnetic excitations reminiscent of other Fe-pnictides. Conversely, the spin excitations in FeSe/STO are gapped, dispersionless, and significantly hardened relative to its bulk counterpart. By comparing our RIXS results with simulations of a bilayer Hubbard model, we connect the evolution of the spin excitations to the Fermiology of the two systems revealing a remarkable reconfiguration of spin excitations in FeSe/STO, essential to understand the role of spin fluctuations in the pairing mechanism. Here, Pelliciari et al. present resonant inelastic X-ray scattering on monolayer samples of unconventional superconductor FeSe, finding evidence for gapped and dispersionless spin excitations. These experiments are very difficult due to the extremely small scattering volume of the FeSe monolayer.
Collapse
|