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Yan L, Bu K, Li Z, Zhang Z, Xia W, Li M, Li N, Guan J, Liu X, Ning J, Zhang D, Guo Y, Wang X, Yang W. Double Superconducting Dome of Quasi Two-Dimensional TaS 2 in Non-Centrosymmetric van der Waals Heterostructure. NANO LETTERS 2024; 24:6002-6009. [PMID: 38739273 DOI: 10.1021/acs.nanolett.4c00579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
Two-dimensional van der Waals heterostructures (2D-vdWHs) based on transition metal dichalcogenides (TMDs) provide unparalleled control over electronic properties. However, the interlayer coupling is challenged by the interfacial misalignment and defects, which hinders a comprehensive understanding of the intertwined electronic orders, especially superconductivity and charge density wave (CDW). Here, by using pressure to regulate the interlayer coupling of non-centrosymmetric 6R-TaS2 vdWHs, we observe an unprecedented phase diagram in TMDs. This phase diagram encompasses successive suppression of the original CDW states from alternating H-layer and T-layer configurations, the emergence and disappearance of a new CDW-like state, and a double superconducting dome induced by different interlayer coupling effects. These results not only illuminate the crucial role of interlayer coupling in shaping the complex phase diagram of TMD systems but also pave a new avenue for the creation of a novel family of bulk heterostructures with customized 2D properties.
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Affiliation(s)
- Limin Yan
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
- School of Science, Inner Mongolia University of Science and Technology, Baotou 014010, People's Republic of China
- State Key Laboratory of Superhard Materials, Department of Physics, Jilin University, Changchun 130012, People's Republic of China
| | - Kejun Bu
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
| | - Zhongyang Li
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Zihan Zhang
- State Key Laboratory of Superhard Materials, Department of Physics, Jilin University, Changchun 130012, People's Republic of China
| | - Wei Xia
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Mingtao Li
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
| | - Nana Li
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
| | - Jiayi Guan
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
- School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Xuqiang Liu
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
| | - Jiahao Ning
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
| | - Dongzhou Zhang
- GSECARS, University of Chicago, 9700 S. Cass Avenue, Argonne, Illinois 60439, United States
| | - Yanfeng Guo
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Xin Wang
- State Key Laboratory of Superhard Materials, Department of Physics, Jilin University, Changchun 130012, People's Republic of China
| | - Wenge Yang
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
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Time-reversal symmetry breaking in the Fe-chalcogenide superconductors. Proc Natl Acad Sci U S A 2021; 118:2007241118. [PMID: 33436408 DOI: 10.1073/pnas.2007241118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Topological superconductivity has been sought in a variety of heterostructure systems, the interest being that a material displaying such a phenomenon could prove to be the ideal platform to support Majorana fermions, which in turn could be the basis for advanced qubit technologies. Recently, the high-Tc family of superconductors, FeTe1-xSex, have been shown to exhibit the property of topological superconductivity and further, evidence has been found for the presence of Majorana fermions. We have studied the interplay of topology, magnetism, and superconductivity in the FeTe1-x Se x family using high-resolution laser-based photoemission. At the bulk superconducting transition, a gap opens at the chemical potential as expected. However, a second gap is observed to open at the Dirac point in the topological surface state. The associated mass acquisition in the topological state points to time-reversal symmetry breaking, probably associated with the formation of ferromagnetism in the surface layer. The presence of intrinsic ferromagnetism combined with strong spin-orbit coupling provides an ideal platform for a range of exotic topological phenomena.
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Song C, Li X, Jiang Y, Wang X, Yao J, Meng S, Zhang J. Real-Space Imaging of Orbital Selectivity on SrTiO 3(001) Surface. ACS APPLIED MATERIALS & INTERFACES 2019; 11:37279-37284. [PMID: 31529959 DOI: 10.1021/acsami.9b11724] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Real-space access of the orbital degree of freedom in complex oxides is still challenging due to intricate electronic hybridization. Here, we report a direct observation of reproducible orbital-selective tunneling on a novel SrTiO3(001) surface by scanning tunneling microscopy. The electronic structures reversibly switch between two different sets of symmetries depending on the sample bias, which is accompanied by a remarkable change in energy-dependent spectroscopy data. Tunneling spectrum combined with density functional theory calculations elucidates that symmetry-breaking at the surface determines the crystal-splitting field of eg/t2g orbitals with a strong in-plane anisotropy so that electrons alternatingly fill eg and t2g orbitals during the imaging process with different biases. This surface superstructure provides a new strategy toward understanding orbital textures and orbital selectivity in complex oxides.
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Affiliation(s)
- Chuangye Song
- Department of Physics , Beijing Normal University , Beijing 100875 , China
| | - Xuanyi Li
- Institute of Physics , Chinese Academic of Science , Beijing 100190 , China
- School of Physics , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Ying Jiang
- International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
| | - Xi Wang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Department of Physics, School of Science , Beijing Jiaotong University , Beijing 100044 , China
- Chemistry and Chemical Engineering Guangdong Laboratory , Shantou 515031 , China
| | - Jiannian Yao
- Chemistry and Chemical Engineering Guangdong Laboratory , Shantou 515031 , China
- Key Laboratory of Photochemistry, Institute of Chemistry , Chinese Academy of Science , Beijing 100190 , China
| | - Sheng Meng
- Institute of Physics , Chinese Academic of Science , Beijing 100190 , China
- School of Physics , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Jinxing Zhang
- Department of Physics , Beijing Normal University , Beijing 100875 , China
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Liu X, Tao R, Ren M, Chen W, Yao Q, Wolf T, Yan Y, Zhang T, Feng D. Evidence of nematic order and nodal superconducting gap along [110] direction in RbFe 2As 2. Nat Commun 2019; 10:1039. [PMID: 30833562 PMCID: PMC6399313 DOI: 10.1038/s41467-019-08962-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 02/12/2019] [Indexed: 11/09/2022] Open
Abstract
Unconventional superconductivity often intertwines with various forms of order, such as the nematic order which breaks the rotational symmetry of the lattice. Here we report a scanning tunneling microscopy study on RbFe2As2, a heavily hole-doped Fe-based superconductor (FeSC). We observe significant symmetry breaking in its electronic structure and magnetic vortex which differentiates the (π, π) and (π, -π) directions of the unfolded Brillouin zone. It is thus a novel nematic state, distinct from the nematicity of undoped/lightly-doped FeSCs which breaks the (π, 0)/(0, π) equivalence. Moreover, we observe a clear V-shaped superconducting gap. The gap is suppressed on surface Rb vacancies and step edges, and the suppression is particularly strong at the [110]-oriented edges. This is possibly due to a \documentclass[12pt]{minimal}
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\begin{document}$${{d}}_{{{x}}^2 - {{y}}^2}$$\end{document}dx2-y2 like pairing component with nodes along the [110] directions. Our results thus highlight the intimate connection between nematicity and superconducting pairing in iron-based superconductors. Exotic electronic order may emerge and intertwine with superconductivity in iron-based superconductors. Here, the authors observe asymmetric electronic and superconducting gap structure in heavily hole-doped RbFe2As2 along the (π, π) and (π, -π) directions in reciprocal space, suggesting a novel (π, π) nematic phase emerging.
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Affiliation(s)
- Xi Liu
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Ran Tao
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Mingqiang Ren
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Wei Chen
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Qi Yao
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Thomas Wolf
- Institute for Solid State Physics, Karlsruhe Institute of Technology, D-76021, Karlsruhe, Germany
| | - Yajun Yan
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Tong Zhang
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, China.
| | - Donglai Feng
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, China.
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Yim CM, Trainer C, Aluru R, Chi S, Hardy WN, Liang R, Bonn D, Wahl P. Discovery of a strain-stabilised smectic electronic order in LiFeAs. Nat Commun 2018; 9:2602. [PMID: 29973598 PMCID: PMC6031620 DOI: 10.1038/s41467-018-04909-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 06/04/2018] [Indexed: 11/09/2022] Open
Abstract
In many high temperature superconductors, small orthorhombic distortions of the lattice structure result in surprisingly large symmetry breaking of the electronic states and macroscopic properties, an effect often referred to as nematicity. To directly study the impact of symmetry-breaking lattice distortions on the electronic states, using low-temperature scanning tunnelling microscopy we image at the atomic scale the influence of strain-tuned lattice distortions on the correlated electronic states in the iron-based superconductor LiFeAs, a material which in its ground state is tetragonal with four-fold (C4) symmetry. Our experiments uncover a new strain-stabilised modulated phase which exhibits a smectic order in LiFeAs, an electronic state which not only breaks rotational symmetry but also reduces translational symmetry. We follow the evolution of the superconducting gap from the unstrained material with C4 symmetry through the new smectic phase with two-fold (C2) symmetry and charge-density wave order to a state where superconductivity is completely suppressed.
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Affiliation(s)
- Chi Ming Yim
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - Christopher Trainer
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - Ramakrishna Aluru
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - Shun Chi
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Walter N Hardy
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Ruixing Liang
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Doug Bonn
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Peter Wahl
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK.
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Hanaguri T, Iwaya K, Kohsaka Y, Machida T, Watashige T, Kasahara S, Shibauchi T, Matsuda Y. Two distinct superconducting pairing states divided by the nematic end point in FeSe 1-x S x. SCIENCE ADVANCES 2018; 4:eaar6419. [PMID: 29806028 PMCID: PMC5969813 DOI: 10.1126/sciadv.aar6419] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 04/12/2018] [Indexed: 06/08/2023]
Abstract
Unconventional superconductivity often competes or coexists with other electronic orders. In iron-based superconductors, a central issue has been the relationship between superconductivity and electronic nematicity, spontaneous breaking of the lattice rotational symmetry. Using spectroscopic-imaging scanning tunneling microscopy, we simultaneously investigated the electronic structure and the superconducting gap in FeSe1-x S x , where the nematicity diminishes above the nematic end point (NEP) at x = 0.17. The nematic band structure appears as anisotropic quasiparticle-interference patterns that gradually become isotropic with increasing x without anomalies at the NEP. By contrast, the superconducting gap, which is intact in the nematic phase, discontinuously shrinks above the NEP. This implies that the presence or absence of nematicity results in two distinct pairing states, whereas the pairing interaction is insensitive to the strength of nematicity.
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Affiliation(s)
- Tetsuo Hanaguri
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Katsuya Iwaya
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Yuhki Kohsaka
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Tadashi Machida
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | | | | | - Takasada Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - Yuji Matsuda
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
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