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Yao Q, Shen DW, Wen CHP, Hua CQ, Zhang LQ, Wang NZ, Niu XH, Chen QY, Dudin P, Lu YH, Zheng Y, Chen XH, Wan XG, Feng DL. Charge Transfer Effects in Naturally Occurring van der Waals Heterostructures (PbSe)_{1.16}(TiSe_{2})_{m} (m=1, 2). PHYSICAL REVIEW LETTERS 2018; 120:106401. [PMID: 29570327 DOI: 10.1103/physrevlett.120.106401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Indexed: 06/08/2023]
Abstract
van der Waals heterostructures (VDWHs) exhibit rich properties and thus has potential for applications, and charge transfer between different layers in a heterostructure often dominates its properties and device performance. It is thus critical to reveal and understand the charge transfer effects in VDWHs, for which electronic structure measurements have proven to be effective. Using angle-resolved photoemission spectroscopy, we studied the electronic structures of (PbSe)_{1.16}(TiSe_{2})_{m} (m=1, 2), which are naturally occurring VDWHs, and discovered several striking charge transfer effects. When the thickness of the TiSe_{2} layers is halved from m=2 to m=1, the amount of charge transferred increases unexpectedly by more than 250%. This is accompanied by a dramatic drop in the electron-phonon interaction strength far beyond the prediction by first-principles calculations and, consequently, superconductivity only exists in the m=2 compound with strong electron-phonon interaction, albeit with lower carrier density. Furthermore, we found that the amount of charge transferred in both compounds is nearly halved when warmed from below 10 K to room temperature, due to the different thermal expansion coefficients of the constituent layers of these misfit compounds. These unprecedentedly large charge transfer effects might widely exist in VDWHs composed of metal-semiconductor contacts; thus, our results provide important insights for further understanding and applications of VDWHs.
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Affiliation(s)
- Q Yao
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, Shanghai 200050, China
- Collaborative Innovation Centre of Advanced Microstructures, Nanjing 210093, China
| | - D W Shen
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, Shanghai 200050, China
- CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, China
| | - C H P Wen
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
- Collaborative Innovation Centre of Advanced Microstructures, Nanjing 210093, China
| | - C Q Hua
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - L Q Zhang
- Collaborative Innovation Centre of Advanced Microstructures, Nanjing 210093, China
- National Laboratory of Solid State Microstructures, College of Physics, Nanjing University, Nanjing 210093, China
| | - N Z Wang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics and Key Laboratory of Strongly-coupled Quantum Matter Physics, University of Science and Technology of China, Hefei 230026, China
| | - X H Niu
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
- Collaborative Innovation Centre of Advanced Microstructures, Nanjing 210093, China
| | - Q Y Chen
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
- Collaborative Innovation Centre of Advanced Microstructures, Nanjing 210093, China
| | - P Dudin
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Y H Lu
- State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027, China
| | - Y Zheng
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - X H Chen
- Collaborative Innovation Centre of Advanced Microstructures, Nanjing 210093, China
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics and Key Laboratory of Strongly-coupled Quantum Matter Physics, University of Science and Technology of China, Hefei 230026, China
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - X G Wan
- Collaborative Innovation Centre of Advanced Microstructures, Nanjing 210093, China
- National Laboratory of Solid State Microstructures, College of Physics, Nanjing University, Nanjing 210093, China
| | - D L Feng
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
- Collaborative Innovation Centre of Advanced Microstructures, Nanjing 210093, China
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Zhu Z, Cheng Y, Schwingenschlögl U. Pressure controlled transition into a self-induced topological superconducting surface state. Sci Rep 2014; 4:4025. [PMID: 24504005 PMCID: PMC3916898 DOI: 10.1038/srep04025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 01/17/2014] [Indexed: 11/09/2022] Open
Abstract
Ab-initio calculations show a pressure induced trivial-nontrivial-trivial topological phase transition in the normal state of 1T-TiSe2. The pressure range in which the nontrivial phase emerges overlaps with that of the superconducting ground state. Thus, topological superconductivity can be induced in protected surface states by the proximity effect of superconducting bulk states. This kind of self-induced topological surface superconductivity is promising for a realization of Majorana fermions due to the absence of lattice and chemical potential mismatches. For appropriate electron doping, the formation of the topological superconducting surface state in 1T-TiSe2 becomes accessible to experiments as it can be controlled by pressure.
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Affiliation(s)
- Zhiyong Zhu
- Physical Sciences and Engineering Division, KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Yingchun Cheng
- Physical Sciences and Engineering Division, KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Udo Schwingenschlögl
- Physical Sciences and Engineering Division, KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia
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d-Wave Superconductivity and s-Wave Charge Density Waves: Coexistence between Order Parameters of Different Origin and Symmetry. Symmetry (Basel) 2011. [DOI: 10.3390/sym3040699] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A review of the theory describing the coexistence between d-wave superconductivity and s-wave charge-density-waves (CDWs) is presented. The CDW gapping is identified with pseudogapping observed in high-Tc oxides. According to the cuprate specificity, the analysis is carried out for the two-dimensional geometry of the Fermi surface (FS). Phase diagrams on the σ0 − α plane—here, σ0 is the ratio between the energy gaps in the parent pure CDW and superconducting states, and the quantity 2α is connected with the degree of dielectric (CDW) FS gapping—were obtained for various possible configurations of the order parameters in the momentum space. Relevant tunnel and photoemission experimental data for high-Tc oxides are compared with theoretical predictions. A brief review of the results obtained earlier for the coexistence between s-wave superconductivity and CDWs is also given.
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Lumata LL, Choi KY, Brooks JS, Reyes AP, Kuhns PL, Wu G, Chen XH. 77Se and 63Cu NMR studies of the electronic correlations in CuxTiSe2 (x = 0.05, 0.07). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:295601. [PMID: 21399313 DOI: 10.1088/0953-8984/22/29/295601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report a (77)Se and (63)Cu nuclear magnetic resonance (NMR) investigation on the charge-density-wave (CDW) superconductor Cu(x)TiSe(2) (x = 0.05 and 0.07). At high magnetic fields where superconductivity is suppressed, the temperature dependence of (77)Se and (63)Cu spin-lattice relaxation rates 1/T(1) follow a linear relation. The slope of (77)Se 1/T(1) versus T increases with the Cu doping. This can be described by a modified Korringa relation which suggests the significance of electronic correlations and the Se 4p- and Ti 3d-band contribution to the density of states at the Fermi level in the studied compounds.
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Affiliation(s)
- L L Lumata
- Department of Physics, Florida State University, Tallahassee, FL 32310, USA.
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Kusmartseva AF, Sipos B, Berger H, Forró L, Tutis E. Pressure induced superconductivity in pristine 1T-TiSe2. PHYSICAL REVIEW LETTERS 2009; 103:236401. [PMID: 20366159 DOI: 10.1103/physrevlett.103.236401] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Indexed: 05/25/2023]
Abstract
The interplay between superconductivity and the charge-density wave (CDW) state in pure 1T-TiSe(2) is examined through a high-pressure study extending up to pressures of 10 GPa between sub-Kelvin and room temperatures. At a critical pressure of 2 GPa a superconducting phase sets in and persists up to pressures of 4 GPa. The maximum superconducting transition temperature is 1.8 K. These findings complement the recent discovery of superconductivity in copper-intercalated 1T-TiSe(2). The comparisons of the normal state and superconducting properties of the two systems reveal the possibility that the emergent electronic state qualitatively depends on the manner in which the CDW state is destabilized, making this a unique example where two different superconducting domes are obtained by two different methods from the same parent compound.
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Affiliation(s)
- A F Kusmartseva
- Ecole Polytechnique Federale de Lausanne, IPMC, CH-1015 Lausanne, Switzerland
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