1
|
Li P, Liao S, Wang Z, Li H, Su S, Zhang J, Chen Z, Jiang Z, Liu Z, Yang L, Huai L, He J, Cui S, Sun Z, Yan Y, Cao G, Shen D, Jiang J, Feng D. Evidence of electron interaction with an unidentified bosonic mode in superconductor CsCa 2Fe 4As 4F 2. Nat Commun 2024; 15:6433. [PMID: 39085266 PMCID: PMC11291980 DOI: 10.1038/s41467-024-50833-9] [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: 02/01/2024] [Accepted: 07/22/2024] [Indexed: 08/02/2024] Open
Abstract
The kink structure in band dispersion usually refers to a certain electron-boson interaction, which is crucial in understanding the pairing in unconventional superconductors. Here we report the evidence of the observation of a kink structure in Fe-based superconductor CsCa2Fe4As4F2 using angle-resolved photoemission spectroscopy. The kink shows an orbital selective and momentum dependent behavior, which is located at 15 meV below Fermi level along the Γ - M direction at the band with dxz orbital character and vanishes when approaching the Γ - X direction, correlated with a slight decrease of the superconducting gap. Most importantly, this kink structure disappears when the superconducting gap closes, indicating that the corresponding bosonic mode (~ 9 ± 1 meV) is closely related to superconductivity. However, the origin of this mode remains unidentified, since it cannot be related to phonons or the spin resonance mode (~15 meV) observed by inelastic neutron scattering. The behavior of this mode is rather unique and challenges our present understanding of the superconducting paring mechanism of the bilayer FeAs-based superconductors.
Collapse
Affiliation(s)
- Peng Li
- Shool of Emerging Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Sen Liao
- Shool of Emerging Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Zhicheng Wang
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing, 211189, China
| | - Huaxun Li
- School of Physics, Zhejiang University, Hangzhou, 310058, China
| | - Shiwu Su
- Shool of Emerging Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Jiakang Zhang
- Shool of Emerging Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Ziyuan Chen
- Shool of Emerging Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Zhicheng Jiang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230026, China
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Zhengtai Liu
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201210, China
| | - Lexian Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Linwei Huai
- CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Junfeng He
- CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Shengtao Cui
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230026, China
| | - Zhe Sun
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230026, China
| | - Yajun Yan
- Shool of Emerging Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Guanghan Cao
- School of Physics, Zhejiang University, Hangzhou, 310058, China
| | - Dawei Shen
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230026, China
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, 230026, China
| | - Juan Jiang
- Shool of Emerging Technology, University of Science and Technology of China, Hefei, 230026, China.
| | - Donglai Feng
- Shool of Emerging Technology, University of Science and Technology of China, Hefei, 230026, China.
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230026, China.
- 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.
| |
Collapse
|
2
|
Zhong Y, Liu J, Wu X, Guguchia Z, Yin JX, Mine A, Li Y, Najafzadeh S, Das D, Mielke C, Khasanov R, Luetkens H, Suzuki T, Liu K, Han X, Kondo T, Hu J, Shin S, Wang Z, Shi X, Yao Y, Okazaki K. Nodeless electron pairing in CsV 3Sb 5-derived kagome superconductors. Nature 2023; 617:488-492. [PMID: 37100906 DOI: 10.1038/s41586-023-05907-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 03/01/2023] [Indexed: 04/28/2023]
Abstract
The newly discovered kagome superconductors represent a promising platform for investigating the interplay between band topology, electronic order and lattice geometry1-9. Despite extensive research efforts on this system, the nature of the superconducting ground state remains elusive10-17. In particular, consensus on the electron pairing symmetry has not been achieved so far18-20, in part owing to the lack of a momentum-resolved measurement of the superconducting gap structure. Here we report the direct observation of a nodeless, nearly isotropic and orbital-independent superconducting gap in the momentum space of two exemplary CsV3Sb5-derived kagome superconductors-Cs(V0.93Nb0.07)3Sb5 and Cs(V0.86Ta0.14)3Sb5-using ultrahigh-resolution and low-temperature angle-resolved photoemission spectroscopy. Remarkably, such a gap structure is robust to the appearance or absence of charge order in the normal state, tuned by isovalent Nb/Ta substitutions of V. Our comprehensive characterizations of the superconducting gap provide indispensable information on the electron pairing symmetry of kagome superconductors, and advance our understanding of the superconductivity and intertwined electronic orders in quantum materials.
Collapse
Affiliation(s)
- Yigui Zhong
- Institute for Solid States Physics, The University of Tokyo, Kashiwa, Japan
| | - Jinjin Liu
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, China
| | - Xianxin Wu
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China
| | - Zurab Guguchia
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - J-X Yin
- Laboratory for Quantum Emergence, Department of Physics, Southern University of Science and Technology, Shenzhen, China
- Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen, China
| | - Akifumi Mine
- Institute for Solid States Physics, The University of Tokyo, Kashiwa, Japan
| | - Yongkai Li
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, China
- Material Science Center, Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing, China
| | - Sahand Najafzadeh
- Institute for Solid States Physics, The University of Tokyo, Kashiwa, Japan
| | - Debarchan Das
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - Charles Mielke
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - Rustem Khasanov
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - Hubertus Luetkens
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - Takeshi Suzuki
- Institute for Solid States Physics, The University of Tokyo, Kashiwa, Japan
| | - Kecheng Liu
- Institute for Solid States Physics, The University of Tokyo, Kashiwa, Japan
| | - Xinloong Han
- Kavli Institute of Theoretical Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Takeshi Kondo
- Institute for Solid States Physics, The University of Tokyo, Kashiwa, Japan
- Trans-scale Quantum Science Institute, The University of Tokyo, Tokyo, Japan
| | - Jiangping Hu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Shik Shin
- Institute for Solid States Physics, The University of Tokyo, Kashiwa, Japan
- Office of University Professor, The University of Tokyo, Kashiwa, Japan
| | - Zhiwei Wang
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, China.
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, China.
- Material Science Center, Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing, China.
| | - Xun Shi
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, China.
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, China.
| | - Yugui Yao
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, China
- Material Science Center, Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing, China
| | - Kozo Okazaki
- Institute for Solid States Physics, The University of Tokyo, Kashiwa, Japan.
- Trans-scale Quantum Science Institute, The University of Tokyo, Tokyo, Japan.
- Material Innovation Research Center, The University of Tokyo, Kashiwa, Japan.
| |
Collapse
|
3
|
Ideta S, Johnston S, Yoshida T, Tanaka K, Mori M, Anzai H, Ino A, Arita M, Namatame H, Taniguchi M, Ishida S, Takashima K, Kojima KM, Devereaux TP, Uchida S, Fujimori A. Hybridization of Bogoliubov Quasiparticles between Adjacent CuO_{2} Layers in the Triple-Layer Cuprate Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{10+δ} Studied by Angle-Resolved Photoemission Spectroscopy. PHYSICAL REVIEW LETTERS 2021; 127:217004. [PMID: 34860085 DOI: 10.1103/physrevlett.127.217004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 07/08/2021] [Accepted: 10/20/2021] [Indexed: 06/13/2023]
Abstract
Hybridization of Bogoliubov quasiparticles (BQPs) between the CuO_{2} layers in the triple-layer cuprate high-temperature superconductor Bi_{2}Sr_{2}Cu_{2}Cu_{3}O_{10+δ} is studied by angle-resolved photoemission spectroscopy (ARPES). In the superconducting state, an anticrossing gap opens between the outer- and inner-BQP bands, which we attribute primarily to interlayer single-particle hopping with possible contributions from interlayer Cooper pairing. We find that the d-wave superconducting gap of both BQP bands smoothly develops with momentum without an abrupt jump in contrast to a previous ARPES study. Hybridization between the BQPs also gradually increases in going from the off nodal to the antinodal region, which is explained by the momentum dependence of the interlayer single-particle hopping. As possible mechanisms for the enhancement of the superconducting transition temperature, the hybridization between the BQPs as well as the combination of phonon modes of the triple CuO_{2} layers and spin fluctuations represented by a four-well model are discussed.
Collapse
Affiliation(s)
- S Ideta
- Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- UVSOR-III Synchrotron, Institute for Molecular Science, Okazaki 444-8585, Japan
| | - S Johnston
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - T Yoshida
- Department of Human and Environmental studies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - K Tanaka
- UVSOR-III Synchrotron, Institute for Molecular Science, Okazaki 444-8585, Japan
| | - M Mori
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
| | - H Anzai
- Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8531, Japan
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - A Ino
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
- Department of Education and Creation Engineering, Kurume Institute of Technology, Fukuoka 2286-66, Japan
| | - M Arita
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
| | - H Namatame
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
| | - M Taniguchi
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
| | - S Ishida
- Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - K Takashima
- Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - K M Kojima
- Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- J-PARC Center and Institute of Materials Structure Science, KEK, Tsukuba, Ibaraki 305-0801, Japan
- Centre for Molecular and Materials Science, TRIUMF, 4004 Vancouver, Canada
| | - T P Devereaux
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Laboratory and Stanford University, Menlo Park, California 94025, USA
- Department of Materials Science and Engineering Stanford University, Stanford, California 94305, USA
| | - S Uchida
- Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - A Fujimori
- Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- Department of Applied Physics, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan
| |
Collapse
|
4
|
Unusual Temperature Evolution of Quasiparticle Band Dispersion in Electron-Doped FeSe Films. Symmetry (Basel) 2021. [DOI: 10.3390/sym13020155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The discovery of high-temperature (high-Tc) superconductivity in one-monolayer FeSe on SrTiO3 has attracted tremendous attention. Subsequent studies suggested the importance of cooperation between intra-FeSe-layer and interfacial interactions to enhance Tc. However, the nature of intra-FeSe-layer interactions, which would play a primary role in determining the pairing symmetry, remains unclear. Here we have performed high-resolution angle-resolved photoemission spectroscopy of one-monolayer and alkaline-metal-deposited multilayer FeSe films on SrTiO3, and determined the evolution of quasiparticle band dispersion across Tc. We found that the band dispersion in the superconducting state deviates from the Bogoliubov-quasiparticle dispersion expected from the normal-state band dispersion with a constant gap size. This suggests highly anisotropic pairing originating from small momentum transfer and/or mass renormalization due to electron–boson coupling. This band anomaly is interpreted in terms of the electronic interactions within the FeSe layers that may be related to the high-Tc superconductivity in electron-doped FeSe.
Collapse
|
5
|
Abstract
A translation-invariant (TI) bipolaron theory of superconductivity based, like Bardeen–Cooper–Schrieffer theory, on Fröhlich Hamiltonian is presented. Here the role of Cooper pairs belongs to TI bipolarons which are pairs of spatially delocalized electrons whose correlation length of a coupled state is small. The presence of Fermi surface leads to the stabilization of such states in its vicinity and a possibility of their Bose–Einstein condensation (BEC). The theory provides a natural explanation of the existence of a pseudogap phase preceding the superconductivity and enables one to estimate the temperature of a transition T * from a normal state to a pseudogap one. It is shown that the temperature of BEC of TI bipolarons determines the temperature of a superconducting transition T c which depends not on the bipolaron effective mass but on the ordinary mass of a band electron. This removes restrictions on the upper limit of T c for a strong electron-phonon interaction. A natural explanation is provided for the angular dependence of the superconducting gap which is determined by the angular dependence of the phonon spectrum. It is demonstrated that a lot of experiments on thermodynamic and transport characteristics, Josephson tunneling and angle-resolved photoemission spectroscopy (ARPES) of high-temperature superconductors does not contradict the concept of a TI bipolaron mechanism of superconductivity in these materials. Possible ways of enhancing T c and producing new room-temperature superconductors are discussed on the basis of the theory suggested.
Collapse
|
6
|
Zou C, Hao Z, Li H, Li X, Ye S, Yu L, Lin C, Wang Y. Effect of Structural Supermodulation on Superconductivity in Trilayer Cuprate Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{10+δ}. PHYSICAL REVIEW LETTERS 2020; 124:047003. [PMID: 32058786 DOI: 10.1103/physrevlett.124.047003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 07/24/2019] [Indexed: 06/10/2023]
Abstract
We investigate the spatial and doping evolutions of the superconducting properties of trilayer cuprate Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{10+δ} by using scanning tunneling microscopy and spectroscopy. Both the superconducting coherence peak and gap size exhibit periodic variations with structural supermodulation, but the effect is much more pronounced in the underdoped regime than at optimal doping. Moreover, a new type of tunneling spectrum characterized by two superconducting gaps emerges with increasing doping, and the two-gap features also correlate with the supermodulation. We propose that the interaction between the inequivalent outer and inner CuO_{2} planes is responsible for these novel features that are unique to trilayer cuprates.
Collapse
Affiliation(s)
- Changwei Zou
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Zhenqi Hao
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Haiwei Li
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Xintong Li
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Shusen Ye
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Li Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Chengtian Lin
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Yayu Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
| |
Collapse
|
7
|
Experimental evidence of anomalously large superconducting gap on topological surface state of β-Bi 2Pd film. Sci Bull (Beijing) 2019; 64:1215-1221. [PMID: 36659601 DOI: 10.1016/j.scib.2019.07.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/03/2019] [Accepted: 07/12/2019] [Indexed: 01/21/2023]
Abstract
Connate topological superconductor (TSC) combines topological surface states with nodeless superconductivity in a single material, achieving effective p-wave pairing without interface complication. By combining angle-resolved photoemission spectroscopy and in-situ molecular beam epitaxy, we studied the momentum-resolved superconductivity in β-Bi2Pd film. We found that the superconducting gap of topological surface state (ΔTSS ∼ 3.8 meV) is anomalously enhanced from its bulk value (Δb ∼ 0.8 meV). The ratio of 2ΔTSS/kBTc ∼ 16.3, is substantially larger than the BCS value. By measuring β-Bi2Pd bulk single crystal as a comparison, we clearly observed the upward-shift of chemical potential in the film. In addition, a concomitant increasing of surface weight on the topological surface state was revealed by our first principle calculation, suggesting that the Dirac-fermion-mediated parity mixing may cause this anomalous superconducting enhancement. Our results establish β-Bi2Pd film as a unique case of connate TSCs with a highly enhanced topological superconducting gap, which may stabilize Majorana zero modes at a higher temperature.
Collapse
|
8
|
Stefański P. Properties of the Majorana-state tunneling Josephson junction mediated by an interacting quantum dot. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:185301. [PMID: 30731436 DOI: 10.1088/1361-648x/ab052a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We consider a model of a Josephson junction of two topological superconducting wires mediated by an interacting quantum dot. An additional normal electrode coupled to the dot from the top allows to probe its density of states. The Majorana states adjacent to the dot hybridize across the junction and from a bound state in the dot. The dot is subjected to the effective magnetic field arising from the superposition of the fields driving each wire into topological states, which, dependent on the angle between the fields, introduces variable Zeeman splitting of the dot active level. We show that electron interactions in the dot diminish the characteristic for Majoranas zero bias peak arising in the transverse conductance through the dot and introduce an overall asymmetry of the conductance. They also renormalize the hybridization between the end-state Majoranas in shorter wires. The Majorana spin polarization is determined by the effective magnetic field in the dot. Phase-biased Josephson current exhibits spin polarization in thermal equilibrium, which possesses characteristic [Formula: see text] periodicity, and its sign can be switched when an unpaired Majorana state is present in the junction. We also observe spin-dependent Majorana state 'leaking', which can be controlled by the position of the dot level in energy scale.
Collapse
Affiliation(s)
- Piotr Stefański
- Institute of Molecular Physics of the Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań, Poland
| |
Collapse
|
9
|
Kobiałka A, Ptok A. Electrostatic formation of the Majorana quasiparticles in the quantum dot-nanoring structure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:185302. [PMID: 30703753 DOI: 10.1088/1361-648x/ab03bf] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Zero-energy Majorana quasiparticles can be induced at the edges of low dimensional systems. Non-Abelian statistics of these states make them valid candidates for the realisation of topological quantum computer. From the practical point of view, it is crucial to obtain a system in which an on demand creation and manipulation of this type of bound states is feasible. In this article, we show such a possibility in a setup comprising a quantum nanoring in which we specify a quantum dot region via electrostatic means. The presence of quantum dot can lead to the emergence of Andreev and Majorana bound states in the investigated system. We study the differences between those two types of bound states and the possibility of their manipulation. Moreover, the exact calculation method for spectral function has been proposed, which can be used to study the influence of bound states on the band structure of the proposed system. Using this method, it can be shown that the Majorana bound states, induced at the edge of the system, present themselves as a dispersionless zero-energy flat-band.
Collapse
Affiliation(s)
- Aksel Kobiałka
- Institute of Physics, Maria Curie-Skłodowska University, Plac Marii Skłodowskiej-Curie 1, PL-20031 Lublin, Poland
| | | |
Collapse
|
10
|
Ptok A, Cichy A, Domański T. Quantum engineering of Majorana quasiparticles in one-dimensional optical lattices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:355602. [PMID: 30051875 DOI: 10.1088/1361-648x/aad659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We propose a feasible way of engineering Majorana-type quasiparticles in ultracold fermionic gases on a one-dimensional (1D) optical lattice. For this purpose, imbalanced ultracold atoms interacting by the spin-orbit coupling should be hybridized with a three-dimensional Bose-Einstein condensate molecular cloud. We show that the Majorana-type excitations can be created or annihilated upon constraining the profile of a trapping potential and/or an internal scattering barier. This process is modeled within the Bogoliubov-de Gennes approach. Our study is relevant also to nanoscopic 1D superconductors, where both potentials can be imposed by electrostatic means.
Collapse
Affiliation(s)
- Andrzej Ptok
- Institute of Nuclear Physics, Polish Academy of Sciences, ul. E. Radzikowskiego 152, PL-31342 Kraków, Poland
| | | | | |
Collapse
|
11
|
Boschini F, da Silva Neto EH, Razzoli E, Zonno M, Peli S, Day RP, Michiardi M, Schneider M, Zwartsenberg B, Nigge P, Zhong RD, Schneeloch J, Gu GD, Zhdanovich S, Mills AK, Levy G, Jones DJ, Giannetti C, Damascelli A. Collapse of superconductivity in cuprates via ultrafast quenching of phase coherence. NATURE MATERIALS 2018; 17:416-420. [PMID: 29610487 DOI: 10.1038/s41563-018-0045-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 02/23/2018] [Indexed: 05/26/2023]
Abstract
The possibility of driving phase transitions in low-density condensates through the loss of phase coherence alone has far-reaching implications for the study of quantum phases of matter. This has inspired the development of tools to control and explore the collective properties of condensate phases via phase fluctuations. Electrically gated oxide interfaces1,2, ultracold Fermi atoms3,4 and cuprate superconductors5,6, which are characterized by an intrinsically small phase stiffness, are paradigmatic examples where these tools are having a dramatic impact. Here we use light pulses shorter than the internal thermalization time to drive and probe the phase fragility of the Bi2Sr2CaCu2O8+δ cuprate superconductor, completely melting the superconducting condensate without affecting the pairing strength. The resulting ultrafast dynamics of phase fluctuations and charge excitations are captured and disentangled by time-resolved photoemission spectroscopy. This work demonstrates the dominant role of phase coherence in the superconductor-to-normal state phase transition and offers a benchmark for non-equilibrium spectroscopic investigations of the cuprate phase diagram.
Collapse
Affiliation(s)
- F Boschini
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada.
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada.
| | - E H da Silva Neto
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
- Max Planck Institute for Solid State Research, Stuttgart, Germany
- Department of Physics, University of California, Davis, CA, USA
| | - E Razzoli
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
| | - M Zonno
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
| | - S Peli
- Department of Mathematics and Physics, Università Cattolica del Sacro Cuore, Brescia, Italy
- Interdisciplinary Laboratories for Advanced Materials Physics (ILAMP), Università Cattolica del Sacro Cuore, Brescia, Italy
| | - R P Day
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
| | - M Michiardi
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - M Schneider
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
| | - B Zwartsenberg
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
| | - P Nigge
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
| | - R D Zhong
- Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY, USA
| | - J Schneeloch
- Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY, USA
- Department of Physics & Astronomy, Stony Brook University, Stony Brook, NY, USA
| | - G D Gu
- Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY, USA
| | - S Zhdanovich
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
| | - A K Mills
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
| | - G Levy
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
| | - D J Jones
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada
| | - C Giannetti
- Department of Mathematics and Physics, Università Cattolica del Sacro Cuore, Brescia, Italy
- Interdisciplinary Laboratories for Advanced Materials Physics (ILAMP), Università Cattolica del Sacro Cuore, Brescia, Italy
| | - A Damascelli
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada.
- Quantum Matter Institute, University of British Columbia, Vancouver, BC, Canada.
| |
Collapse
|
12
|
Kiczek B, Ptok A. Influence of the orbital effects on the Majorana quasi-particles in a nanowire. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:495301. [PMID: 29035271 DOI: 10.1088/1361-648x/aa93ab] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Majorana quasi-particles can be realised using magnetic field in the form of diamagnetic (orbital) or paramagnetic effects. In both cases, the magnetic field induces a topologically non-trivial phase of matter. In this paper, the influence of orbital effects on Majorana bound states induced by paramagnetic effects in 1D nanowire is elaborated. The role of orbital effects in density of states and eigenstates of the system is also discussed. Additionally, we show the phase diagram-the magnetic field versus the magnetic flux, which displays a relation between topologically trivial and non-trivial phases. The Majorana bound states existence in the presence of relatively small orbital effects is indicated.
Collapse
Affiliation(s)
- Bartłomiej Kiczek
- Institute of Physics, Maria Curie-Skłodowska University, pl. M. Curie-Skłodowskiej 1, 20-031 Lublin, Poland
| | | |
Collapse
|
13
|
Mou D, Kong T, Meier WR, Lochner F, Wang LL, Lin Q, Wu Y, Bud'ko SL, Eremin I, Johnson DD, Canfield PC, Kaminski A. Enhancement of the Superconducting Gap by Nesting in CaKFe_{4}As_{4}: A New High Temperature Superconductor. PHYSICAL REVIEW LETTERS 2016; 117:277001. [PMID: 28084772 DOI: 10.1103/physrevlett.117.277001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Indexed: 06/06/2023]
Abstract
We use high resolution angle resolved photoemission spectroscopy and density functional theory with measured crystal structure parameters to study the electronic properties of CaKFe_{4}As_{4}. In contrast to the related CaFe_{2}As_{2} compounds, CaKFe_{4}As_{4} has a high T_{c} of 35 K at stochiometric composition. This presents a unique opportunity to study the properties of high temperature superconductivity in the iron arsenides in the absence of doping or substitution. The Fermi surface consists of several hole and electron pockets that have a range of diameters. We find that the values of the superconducting gap are nearly isotropic (within the explored portions of the Brillouin zone), but are significantly different for each of the Fermi surface (FS) sheets. Most importantly, we find that the momentum dependence of the gap magnitude plotted across the entire Brillouin zone displays a strong deviation from the simple cos(k_{x})cos(k_{y}) functional form of the gap function, proposed by the scenario of Cooper pairing driven by a short range antiferromagnetic exchange interaction. Instead, the maximum value of the gap is observed on FS sheets that are closest to the ideal nesting condition, in contrast to previous observations in other ferropnictides. These results provide strong support for the multiband character of superconductivity in CaKFe_{4}As_{4}, in which Cooper pairing forms on the electron and the hole bands interacting via a dominant interband repulsive interaction, enhanced by band nesting.
Collapse
Affiliation(s)
- Daixiang Mou
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Tai Kong
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - William R Meier
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Felix Lochner
- Institut fur Theoretische Physik III, Ruhr-Universitat Bochum, 44801 Bochum, Germany
| | - Lin-Lin Wang
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
| | - Qisheng Lin
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
| | - Yun Wu
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - S L Bud'ko
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Ilya Eremin
- Institut fur Theoretische Physik III, Ruhr-Universitat Bochum, 44801 Bochum, Germany
| | - D D Johnson
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
- Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, USA
| | - P C Canfield
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Adam Kaminski
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| |
Collapse
|
14
|
Hong J, Abergel DSL. A universal explanation of tunneling conductance in exotic superconductors. Sci Rep 2016; 6:31352. [PMID: 27511315 PMCID: PMC4980671 DOI: 10.1038/srep31352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 07/12/2016] [Indexed: 11/30/2022] Open
Abstract
A longstanding mystery in understanding cuprate superconductors is the inconsistency between the experimental data measured by scanning tunneling spectroscopy (STS) and angle-resolved photoemission spectroscopy (ARPES). In particular, the gap between prominent side peaks observed in STS is much bigger than the superconducting gap observed by ARPES measurements. Here, we reconcile the two experimental techniques by generalising a theory which was previously applied to zero-dimensional mesoscopic Kondo systems to strongly correlated two-dimensional (2D) exotic superconductors. We show that the side peaks observed in tunneling conductance measurements in all these materials have a universal origin: They are formed by coherence-mediated tunneling under bias and do not directly reflect the underlying density of states (DOS) of the sample. We obtain theoretical predictions of the tunneling conductance and the density of states of the sample simultaneously and show that for cuprate and pnictide superconductors, the extracted sample DOS is consistent with the superconducting gap measured by ARPES.
Collapse
Affiliation(s)
- Jongbae Hong
- Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon 305-811, Korea
| | - D S L Abergel
- Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-106 91 Stockholm, Sweden.,Center for Quantum Materials, KTH and Nordita, Roslagstullsbacken 11, SE-106 91 Stockholm, Sweden
| |
Collapse
|
15
|
Miyata Y, Nakayama K, Sugawara K, Sato T, Takahashi T. High-temperature superconductivity in potassium-coated multilayer FeSe thin films. NATURE MATERIALS 2015; 14:775-779. [PMID: 26030306 DOI: 10.1038/nmat4302] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 04/21/2015] [Indexed: 06/04/2023]
Abstract
The recent discovery of possible high-temperature (T(c)) superconductivity over 65 K in a monolayer FeSe film on SrTiO3 (refs 1-6) triggered a fierce debate on how superconductivity evolves from bulk to film, because bulk FeSe crystal exhibits a T(c) of no higher than 10 K (ref. 7). However, the difficulty in controlling the carrier density and the number of FeSe layers has hindered elucidation of this problem. Here, we demonstrate that deposition of potassium onto FeSe films markedly expands the accessible doping range towards the heavily electron-doped region. Intriguingly, we have succeeded in converting non-superconducting films with various thicknesses into superconductors with T(c) as high as 48 K. We also found a marked increase in the magnitude of the superconducting gap on decreasing the FeSe film thickness, indicating that the interface plays a crucial role in realizing the high-temperature superconductivity. The results presented provide a new strategy to enhance and optimize T(c) in ultrathin films of iron-based superconductors.
Collapse
Affiliation(s)
- Y Miyata
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
| | - K Nakayama
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
| | - K Sugawara
- WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - T Sato
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
| | - T Takahashi
- 1] Department of Physics, Tohoku University, Sendai 980-8578, Japan [2] WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| |
Collapse
|
16
|
From quantum matter to high-temperature superconductivity in copper oxides. Nature 2015; 518:179-86. [PMID: 25673411 DOI: 10.1038/nature14165] [Citation(s) in RCA: 481] [Impact Index Per Article: 53.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/22/2014] [Indexed: 11/09/2022]
Abstract
The discovery of high-temperature superconductivity in the copper oxides in 1986 triggered a huge amount of innovative scientific inquiry. In the almost three decades since, much has been learned about the novel forms of quantum matter that are exhibited in these strongly correlated electron systems. A qualitative understanding of the nature of the superconducting state itself has been achieved. However, unresolved issues include the astonishing complexity of the phase diagram, the unprecedented prominence of various forms of collective fluctuations, and the simplicity and insensitivity to material details of the 'normal' state at elevated temperatures.
Collapse
|
17
|
Chatterjee U, Zhao J, Iavarone M, Di Capua R, Castellan JP, Karapetrov G, Malliakas CD, Kanatzidis MG, Claus H, Ruff JPC, Weber F, van Wezel J, Campuzano JC, Osborn R, Randeria M, Trivedi N, Norman MR, Rosenkranz S. Emergence of coherence in the charge-density wave state of 2H-NbSe2. Nat Commun 2015; 6:6313. [PMID: 25687135 PMCID: PMC4339883 DOI: 10.1038/ncomms7313] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 01/19/2015] [Indexed: 12/02/2022] Open
Abstract
A charge-density wave (CDW) state has a broken symmetry described by a complex order parameter with an amplitude and a phase. The conventional view, based on clean, weak-coupling systems, is that a finite amplitude and long-range phase coherence set in simultaneously at the CDW transition temperature Tcdw. Here we investigate, using photoemission, X-ray scattering and scanning tunnelling microscopy, the canonical CDW compound 2H-NbSe2 intercalated with Mn and Co, and show that the conventional view is untenable. We find that, either at high temperature or at large intercalation, CDW order becomes short-ranged with a well-defined amplitude, which has impacts on the electronic dispersion, giving rise to an energy gap. The phase transition at Tcdw marks the onset of long-range order with global phase coherence, leading to sharp electronic excitations. Our observations emphasize the importance of phase fluctuations in strongly coupled CDW systems and provide insights into the significance of phase incoherence in ‘pseudogap’ states. Charge density waves are described by a complex order parameter whose amplitude is expected to vanish at the transition temperature. This study shows that the transition in 2H-NbSe2 is driven by fluctuations of the phase of the order parameter, with a finite amplitude surviving in the disordered state.
Collapse
Affiliation(s)
- U Chatterjee
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA
| | - J Zhao
- 1] Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA [2] Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, USA
| | - M Iavarone
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - R Di Capua
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - J P Castellan
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Institute of Solid State Physics, Karlsruhe Institute of Technology, PO Box 3640, D-76021 Karlsruhe, Germany
| | - G Karapetrov
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - C D Malliakas
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - M G Kanatzidis
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - H Claus
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J P C Ruff
- 1] Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] CHESS, Cornell University, Ithaca, New York 14853, USA
| | - F Weber
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Institute of Solid State Physics, Karlsruhe Institute of Technology, PO Box 3640, D-76021 Karlsruhe, Germany
| | - J van Wezel
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Institute for Theoretical Physics, University of Amsterdam, Tyndall Avenue, 1090 GL Amsterdam, The Netherlands
| | - J C Campuzano
- 1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA [2] Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, USA
| | - R Osborn
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - M Randeria
- Department of Physics, Ohio State University, Columbus, Ohio 43210, USA
| | - N Trivedi
- Department of Physics, Ohio State University, Columbus, Ohio 43210, USA
| | - M R Norman
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - S Rosenkranz
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| |
Collapse
|
18
|
Miao H, Qian T, Shi X, Richard P, Kim TK, Hoesch M, Xing LY, Wang XC, Jin CQ, Hu JP, Ding H. Observation of strong electron pairing on bands without Fermi surfaces in LiFe1−xCoxAs. Nat Commun 2015; 6:6056. [PMID: 25583450 DOI: 10.1038/ncomms7056] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Accepted: 12/09/2014] [Indexed: 11/10/2022] Open
|
19
|
Hong SH, Bok JM, Zhang W, He J, Zhou XJ, Varma CM, Choi HY. Sharp low-energy feature in single-particle spectra due to forward scattering in d-wave cuprate superconductors. PHYSICAL REVIEW LETTERS 2014; 113:057001. [PMID: 25126930 DOI: 10.1103/physrevlett.113.057001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2013] [Indexed: 06/03/2023]
Abstract
There is an enormous interest in the renormalization of the quasiparticle (qp) dispersion relation of cuprate superconductors both below and above the critical temperature T_{c} because it enables the determination of the fluctuation spectrum to which the qp's are coupled. A remarkable discovery by angle-resolved photoemission spectroscopy (ARPES) is a sharp low-energy feature (LEF) in qp spectra well below the superconducting energy gap but with its energy increasing in proportion to T_{c} and its intensity increasing sharply below T_{c}. This unexpected feature needs to be reconciled with d-wave superconductivity. Here, we present a quantitative analysis of ARPES data from Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} (Bi2212) using Eliashberg equations to show that the qp scattering rate due to the forward scattering impurities far from the Cu-O planes is modified by the energy gap below T_{c} and shows up as the LEF. This is also a necessary step to analyze ARPES data to reveal the spectrum of fluctuations promoting superconductivity.
Collapse
Affiliation(s)
- Seung Hwan Hong
- Department of Physics and Institute for Basic Science Research, SungKyunKwan University, Suwon 440-746, Korea
| | - Jin Mo Bok
- Department of Physics and Institute for Basic Science Research, SungKyunKwan University, Suwon 440-746, Korea
| | - Wentao Zhang
- National Laboratory for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Junfeng He
- National Laboratory for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - X J Zhou
- National Laboratory for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - C M Varma
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Han-Yong Choi
- Department of Physics and Institute for Basic Science Research, SungKyunKwan University, Suwon 440-746, Korea and Asia Pacific Center for Theoretical Physics, Pohang 790-784, Korea
| |
Collapse
|
20
|
Superconductivity in an electron band just above the Fermi level: possible route to BCS-BEC superconductivity. Sci Rep 2014; 4:4109. [PMID: 24576851 PMCID: PMC3937798 DOI: 10.1038/srep04109] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 01/30/2014] [Indexed: 11/08/2022] Open
Abstract
Conventional superconductivity follows Bardeen-Cooper-Schrieffer(BCS) theory of electrons-pairing in momentum-space, while superfluidity is the Bose-Einstein condensation(BEC) of atoms paired in real-space. These properties of solid metals and ultra-cold gases, respectively, are connected by the BCS-BEC crossover. Here we investigate the band dispersions in FeTe(0.6)Se(0.4)(Tc = 14.5 K ~ 1.2 meV) in an accessible range below and above the Fermi level(EF) using ultra-high resolution laser angle-resolved photoemission spectroscopy. We uncover an electron band lying just 0.7 meV (~8 K) above EF at the Γ-point, which shows a sharp superconducting coherence peak with gap formation below Tc. The estimated superconducting gap Δ and Fermi energy [Symbol: see text]F indicate composite superconductivity in an iron-based superconductor, consisting of strong-coupling BEC in the electron band and weak-coupling BCS-like superconductivity in the hole band. The study identifies the possible route to BCS-BEC superconductivity.
Collapse
|
21
|
Okazaki K, Ito Y, Ota Y, Kotani Y, Shimojima T, Kiss T, Watanabe S, Chen CT, Niitaka S, Hanaguri T, Takagi H, Chainani A, Shin S. Evidence for a cos(4φ) modulation of the superconducting energy gap of optimally doped FeTe(0.6)Se(0.4) single crystals using laser angle-resolved photoemission spectroscopy. PHYSICAL REVIEW LETTERS 2012; 109:237011. [PMID: 23368253 DOI: 10.1103/physrevlett.109.237011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Indexed: 06/01/2023]
Abstract
We study the superconducting-gap anisotropy of the Γ-centered hole Fermi surface in optimally doped FeTe(0.6)Se(0.4) (T(c)=14.5 K), using laser-excited angle-resolved photoemission spectroscopy. We observe sharp superconducting (SC) coherence peaks at T=2.5 K. In contrast to earlier angle-resolved photoemission spectroscopy studies but consistent with thermodynamic results, the momentum dependence shows a cos(4φ) modulation of the SC-gap anisotropy. The observed SC-gap anisotropy strongly indicates that the pairing interaction is not a conventional phonon-mediated isotropic one. Instead, the results suggest the importance of second-nearest-neighbor electronic interactions between the iron sites in the framework of s(±)-wave superconductivity.
Collapse
Affiliation(s)
- K Okazaki
- Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Okazaki K, Ota Y, Kotani Y, Malaeb W, Ishida Y, Shimojima T, Kiss T, Watanabe S, Chen CT, Kihou K, Lee CH, Iyo A, Eisaki H, Saito T, Fukazawa H, Kohori Y, Hashimoto K, Shibauchi T, Matsuda Y, Ikeda H, Miyahara H, Arita R, Chainani A, Shin S. Octet-Line Node Structure of Superconducting Order Parameter in KFe2As2. Science 2012; 337:1314-7. [DOI: 10.1126/science.1222793] [Citation(s) in RCA: 198] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
|
23
|
Electronic phase diagram of high-temperature copper oxide superconductors. Proc Natl Acad Sci U S A 2011; 108:9346-9. [PMID: 21606341 DOI: 10.1073/pnas.1101008108] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In order to understand the origin of high-temperature superconductivity in copper oxides, we must understand the normal state from which it emerges. Here, we examine the evolution of the normal state electronic excitations with temperature and carrier concentration in Bi(2)Sr(2)CaCu(2)O(8+δ) using angle-resolved photoemission. In contrast to conventional superconductors, where there is a single temperature scale T(c) separating the normal from the superconducting state, the high-temperature superconductors exhibit two additional temperature scales. One is the pseudogap scale T(∗), below which electronic excitations exhibit an energy gap. The second is the coherence scale T(coh), below which sharp spectral features appear due to increased lifetime of the excitations. We find that T(∗) and T(coh) are strongly doping dependent and cross each other near optimal doping. Thus the highest superconducting T(c) emerges from an unusual normal state that is characterized by coherent excitations with an energy gap.
Collapse
|
24
|
Wen HH, Mu G, Luo H, Yang H, Shan L, Ren C, Cheng P, Yan J, Fang L. Specific-heat measurement of a residual superconducting state in the normal state of underdoped Bi_{2}Sr_{2-x}La_{x}CuO_{6+delta} cuprate superconductors. PHYSICAL REVIEW LETTERS 2009; 103:067002. [PMID: 19792597 DOI: 10.1103/physrevlett.103.067002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Indexed: 05/28/2023]
Abstract
We have measured the magnetic field and temperature dependence of specific heat on Bi_{2}Sr_{2-x}La_{x}CuO_{6+delta} single crystals in wide doping and temperature regions. The superconductivity related specific-heat coefficient gamma_{sc} and entropy S_{sc} are determined. It is found that gamma_{sc} has a humplike anomaly at T_{c} and behaves as a long tail which persists far into the normal state for the underdoped samples, but for the heavily overdoped samples the anomaly ends sharply just near T_{c}. Interestingly, we found that the entropy associated with superconductivity is roughly conserved when and only when the long tail part in the normal state is taken into account for the underdoped samples, indicating the residual superconductivity above T_{c}.
Collapse
Affiliation(s)
- Hai-Hu Wen
- National Laboratory for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080, People's Republic of China
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Emergence of preformed Cooper pairs from the doped Mott insulating state in Bi2Sr2CaCu2O8+delta. Nature 2008; 456:77-80. [PMID: 18987738 DOI: 10.1038/nature07400] [Citation(s) in RCA: 196] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 08/29/2008] [Indexed: 11/08/2022]
Abstract
Superconductors are characterized by an energy gap that represents the energy needed to break the pairs of electrons (Cooper pairs) apart. At temperatures considerably above those associated with superconductivity, the high-transition-temperature copper oxides have an additional 'pseudogap'. It has been unclear whether this represents preformed pairs of electrons that have not achieved the coherence necessary for superconductivity, or whether it reflects some alternative ground state that competes with superconductivity. Paired electrons should display particle-hole symmetry with respect to the Fermi level (the energy of the highest occupied level in the electronic system), but competing states need not show such symmetry. Here we report a photoemission study of the underdoped copper oxide Bi(2)Sr(2)CaCu(2)O(8+delta) that shows the opening of a symmetric gap only in the anti-nodal region, contrary to the expectation that pairing would take place in the nodal region. It is therefore evident that the pseudogap does reflect the formation of preformed pairs of electrons and that the pairing occurs only in well-defined directions of the underlying lattice.
Collapse
|
26
|
Kanigel A, Chatterjee U, Randeria M, Norman MR, Koren G, Kadowaki K, Campuzano JC. Evidence for pairing above the transition temperature of cuprate superconductors from the electronic dispersion in the pseudogap phase. PHYSICAL REVIEW LETTERS 2008; 101:137002. [PMID: 18851483 DOI: 10.1103/physrevlett.101.137002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Indexed: 05/26/2023]
Abstract
In the underdoped high temperature superconductors, instead of a complete Fermi surface above Tc, only disconnected Fermi arcs appear, separated by regions that still exhibit an energy gap. We show that in this pseudogap phase, the energy-momentum relation of electronic excitations near EF behaves like the dispersion of a normal metal on the Fermi arcs, but like that of a superconductor in the gapped regions. We argue that this dichotomy in the dispersion is difficult to reconcile with a competing order parameter, but is consistent with pairing without condensation.
Collapse
Affiliation(s)
- A Kanigel
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, USA
| | | | | | | | | | | | | |
Collapse
|
27
|
Wei J, Zhang Y, Ou HW, Xie BP, Shen DW, Zhao JF, Yang LX, Arita M, Shimada K, Namatame H, Taniguchi M, Yoshida Y, Eisaki H, Feng DL. Superconducting coherence peak in the electronic excitations of a single-layer Bi2Sr1.6La0.4CuO6+delta cuprate superconductor. PHYSICAL REVIEW LETTERS 2008; 101:097005. [PMID: 18851643 DOI: 10.1103/physrevlett.101.097005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Indexed: 05/26/2023]
Abstract
Angle resolved photoemission spectroscopy study is reported on a high quality optimally doped Bi2Sr1.6La0.4CuO6+delta high-Tc superconductor. In the antinodal region with a maximal d-wave gap, the symbolic superconducting coherence peak, which has been widely observed in multi-CuO2-layer cuprate superconductors, is unambiguously observed in a single-layer system. The associated peak-dip separation is just about 19 meV, which is much smaller than its counterparts in multilayered compounds, but correlates with the energy scales of spin excitations in single-layer cuprates.
Collapse
Affiliation(s)
- J Wei
- Department of Physics, Surface Physics Laboratory (National Key Laboratory), Fudan University, Shanghai 200433, People's Republic of China
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Chen XJ, Struzhkin VV, Wu Z, Lin HQ, Hemley RJ, Mao HK. Unified picture of the oxygen isotope effect in cuprate superconductors. Proc Natl Acad Sci U S A 2007; 104:3732-5. [PMID: 17360421 PMCID: PMC1820652 DOI: 10.1073/pnas.0611473104] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
High-temperature superconductivity in cuprates was discovered almost exactly 20 years ago, but a satisfactory theoretical explanation for this phenomenon is still lacking. The isotope effect has played an important role in establishing electron-phonon interaction as the dominant interaction in conventional superconductors. Here we present a unified picture of the oxygen isotope effect in cuprate superconductors based on a phonon-mediated d-wave pairing model within the Bardeen-Cooper-Schrieffer theory. We show that this model accounts for the magnitude of the isotope exponent as functions of the doping level as well as the variation between different cuprate superconductors. The isotope effect on the superconducting transition is also found to resemble the effect of pressure on the transition. These results indicate that the role of phonons should not be overlooked for explaining the superconductivity in cuprates.
Collapse
Affiliation(s)
- Xiao-Jia Chen
- Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA.
| | | | | | | | | | | |
Collapse
|
29
|
Ribeiro TC, Wen XG. Tunneling spectra of layered strongly correlated d-wave superconductors. PHYSICAL REVIEW LETTERS 2006; 97:057003. [PMID: 17026133 DOI: 10.1103/physrevlett.97.057003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Indexed: 05/12/2023]
Abstract
Tunneling conductance experiments on cuprate superconductors exhibit a large diversity of spectra that appear in different nanosized regions of inhomogeneous samples. In this Letter, we use a mean-field approach to the tt't''J model in order to address the features in these spectra that deviate from the BCS paradigm, namely, the bias sign asymmetry at high bias, the generic lack of evidence for the van Hove singularity, and the absence of coherence peaks at low dopings. We conclude that these features can be reproduced in homogeneous layered d-wave superconductors solely due to a proximate Mott insulating transition. We also establish the connection between the above tunneling spectral features and the strong renormalization of the electron dispersion around (0, pi) and (pi, 0) and the momentum space anisotropy of electronic states observed in angle-resolved photoemission spectroscopy experiments.
Collapse
Affiliation(s)
- Tiago C Ribeiro
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | | |
Collapse
|
30
|
Kouzakov KA, Berakdar J. Photoinduced emission of cooper pairs from superconductors. PHYSICAL REVIEW LETTERS 2003; 91:257007. [PMID: 14754144 DOI: 10.1103/physrevlett.91.257007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Indexed: 05/24/2023]
Abstract
Under certain conditions specified in this work, a Cooper pair can be emitted from a superconductor upon the absorption of one ultraviolet photon. The spectra of the excited electron pair carry direct information on the energy and angular pair correlation. These statements are concluded from a formal and numerical analysis based on the Bardeen-Cooper-Schrieffer theory for superconductivity.
Collapse
|