1
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Liu R, Zhang W, Wei Y, Tao Z, Asmara TC, Li Y, Strocov VN, Yu R, Si Q, Schmitt T, Lu X. Nematic Spin Correlations Pervading the Phase Diagram of FeSe_{1-x}S_{x}. PHYSICAL REVIEW LETTERS 2024; 132:016501. [PMID: 38242670 DOI: 10.1103/physrevlett.132.016501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Accepted: 12/08/2023] [Indexed: 01/21/2024]
Abstract
We use resonant inelastic x-ray scattering (RIXS) at the Fe-L_{3} edge to study the spin excitations of uniaxial-strained and unstrained FeSe_{1-x}S_{x} (0≤x≤0.21) samples. The measurements on unstrained samples reveal dispersive spin excitations in all doping levels, which show only minor doping dependence in energy dispersion, lifetime, and intensity, indicating that high-energy spin excitations are only marginally affected by sulfur doping. RIXS measurements on uniaxial-strained samples reveal that the high-energy spin-excitation anisotropy observed previously in FeSe is also present in the doping range 0200 K in x=0.18 and reaches a maximum around the nematic quantum critical doping (x_{c}≈0.17). Since the spin-excitation anisotropy directly reflects the existence of nematic spin correlations, our results indicate that high-energy nematic spin correlations pervade the regime of nematicity in the phase diagram and are enhanced by the nematic quantum criticality. These results emphasize the essential role of spin fluctuations in driving electronic nematicity and highlight the capability of uniaxial strain in tuning spin excitations in quantum materials hosting strong magnetoelastic coupling and electronic nematicity.
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Affiliation(s)
- Ruixian Liu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Wenliang Zhang
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Yuan Wei
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Zhen Tao
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Teguh C Asmara
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- European X-Ray Free-Electron Laser Facility GmbH, 22869 Schenefeld, Germany
| | - Yi Li
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Vladimir N Strocov
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Rong Yu
- Department of Physics, Renmin University of China, Beijing 100872, China
| | - Qimiao Si
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Thorsten Schmitt
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Xingye Lu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
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2
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Walker M, Scott K, Boyle TJ, Byland JK, Bötzel S, Zhao Z, Day RP, Zhdanovich S, Gorovikov S, Pedersen TM, Klavins P, Damascelli A, Eremin IM, Gozar A, Taufour V, da Silva Neto EH. Electronic stripe patterns near the fermi level of tetragonal Fe(Se,S). NPJ QUANTUM MATERIALS 2023; 8:60. [PMID: 38666239 PMCID: PMC11041788 DOI: 10.1038/s41535-023-00592-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 10/05/2023] [Indexed: 04/28/2024]
Abstract
FeSe1-xSx remains one of the most enigmatic systems of Fe-based superconductors. While much is known about the orthorhombic parent compound, FeSe, the tetragonal samples, FeSe1-xSx with x > 0.17, remain relatively unexplored. Here, we provide an in-depth investigation of the electronic states of tetragonal FeSe0.81S0.19, using scanning tunneling microscopy and spectroscopy (STM/S) measurements, supported by angle-resolved photoemission spectroscopy (ARPES) and theoretical modeling. We analyze modulations of the local density of states (LDOS) near and away from Fe vacancy defects separately and identify quasiparticle interference (QPI) signals originating from multiple regions of the Brillouin zone, including the bands at the zone corners. We also observe that QPI signals coexist with a much stronger LDOS modulation for states near the Fermi level whose period is independent of energy. Our measurements further reveal that this strong pattern appears in the STS measurements as short range stripe patterns that are locally two-fold symmetric. Since these stripe patterns coexist with four-fold symmetric QPI around Fe-vacancies, the origin of their local two-fold symmetry must be distinct from that of nematic states in orthorhombic samples. We explore several aspects related to the stripes, such as the role of S and Fe-vacancy defects, and whether they can be explained by QPI. We consider the possibility that the observed stripe patterns may represent incipient charge order correlations, similar to those observed in the cuprates.
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Affiliation(s)
- M. Walker
- Department of Physics and Astronomy, University of California, Davis, CA USA
- Department of Physics, Yale University, New Haven, CT USA
- Energy Sciences Institute, Yale University, West Haven, CT USA
| | - K. Scott
- Department of Physics, Yale University, New Haven, CT USA
- Energy Sciences Institute, Yale University, West Haven, CT USA
| | - T. J. Boyle
- Department of Physics and Astronomy, University of California, Davis, CA USA
- Department of Physics, Yale University, New Haven, CT USA
- Energy Sciences Institute, Yale University, West Haven, CT USA
| | - J. K. Byland
- Department of Physics and Astronomy, University of California, Davis, CA USA
| | - S. Bötzel
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, Bochum, Germany
| | - Z. Zhao
- Department of Physics and Astronomy, University of California, Davis, CA USA
| | - R. P. Day
- Quantum Matter Institute, University of British Columbia, Vancouver, BC Canada
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC Canada
| | - S. Zhdanovich
- Quantum Matter Institute, University of British Columbia, Vancouver, BC Canada
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC Canada
| | - S. Gorovikov
- Canadian Light Source, Saskatoon, Saskatchewan Canada
| | | | - P. Klavins
- Department of Physics and Astronomy, University of California, Davis, CA USA
| | - A. Damascelli
- Quantum Matter Institute, University of British Columbia, Vancouver, BC Canada
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC Canada
| | - I. M. Eremin
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, Bochum, Germany
| | - A. Gozar
- Department of Physics, Yale University, New Haven, CT USA
- Energy Sciences Institute, Yale University, West Haven, CT USA
| | - V. Taufour
- Department of Physics and Astronomy, University of California, Davis, CA USA
| | - E. H. da Silva Neto
- Department of Physics and Astronomy, University of California, Davis, CA USA
- Department of Physics, Yale University, New Haven, CT USA
- Energy Sciences Institute, Yale University, West Haven, CT USA
- Department of Applied Physics, Yale University, New Haven, CT USA
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3
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Čulo M, Licciardello S, Ishida K, Mukasa K, Ayres J, Buhot J, Hsu YT, Imajo S, Qiu MW, Saito M, Uezono Y, Otsuka T, Watanabe T, Kindo K, Shibauchi T, Kasahara S, Matsuda Y, Hussey NE. Expanded quantum vortex liquid regimes in the electron nematic superconductors FeSe 1-xS x and FeSe 1-xTe x. Nat Commun 2023; 14:4150. [PMID: 37438333 DOI: 10.1038/s41467-023-39730-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/21/2023] [Indexed: 07/14/2023] Open
Abstract
The quantum vortex liquid (QVL) is an intriguing state of type-II superconductors in which intense quantum fluctuations of the superconducting (SC) order parameter destroy the Abrikosov lattice even at very low temperatures. Such a state has only rarely been observed, however, and remains poorly understood. One of the key questions is the precise origin of such intense quantum fluctuations and the role of nearby non-SC phases or quantum critical points in amplifying these effects. Here we report a high-field magnetotransport study of FeSe1-xSx and FeSe1-xTex which show a broad QVL regime both within and beyond their respective electron nematic phases. A clear correlation is found between the extent of the QVL and the strength of the superconductivity. This comparative study enables us to identify the essential elements that promote the QVL regime in unconventional superconductors and to demonstrate that the QVL regime itself is most extended wherever superconductivity is weakest.
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Affiliation(s)
- M Čulo
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands.
- Institut za fiziku, Bijenička cesta 46, HR-10000, Zagreb, Croatia.
| | - S Licciardello
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands
| | - K Ishida
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - K Mukasa
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - J Ayres
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK
| | - J Buhot
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK
| | - Y-T Hsu
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands
- Center for Theory and Computation, National Tsing Hua University, No. 101, Section. 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan
| | - S Imajo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - M W Qiu
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - M Saito
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - Y Uezono
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan
| | - T Otsuka
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan
| | - T Watanabe
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan
| | - K Kindo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - T Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - S Kasahara
- Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushimanaka, Kita-Ku, Okayama, 700-8530, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Sakyo-Ku, Kyoto, 606-8502, Japan
| | - N E Hussey
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands.
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK.
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4
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Hou Q, Sun L, Sun Y, Shi Z. Review of Single Crystal Synthesis of 11 Iron-Based Superconductors. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4895. [PMID: 37512171 PMCID: PMC10381650 DOI: 10.3390/ma16144895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 06/27/2023] [Accepted: 07/05/2023] [Indexed: 07/30/2023]
Abstract
The 11 system in the iron-based superconducting family has become one of the most extensively studied materials in the research of high-temperature superconductivity, due to their simple structure and rich physical properties. Many exotic properties, such as multiband electronic structure, electronic nematicity, topology and antiferromagnetic order, provide strong support for the theory of high-temperature superconductivity, and have been at the forefront of condensed matter physics in the past decade. One noteworthy aspect is that a high upper critical magnetic field, large critical current density and lower toxicity give the 11 system good application prospects. However, the research on 11 iron-based superconductors faces numerous obstacles, mainly stemming from the challenges associated with producing high-quality single crystals. Since the discovery of FeSe superconductivity in 2008, researchers have made significant progress in crystal growth, overcoming the hurdles that initially impeded their studies. Consequently, they have successfully established the complete phase diagrams of 11 iron-based superconductors, including FeSe1-xTex, FeSe1-xSx and FeTe1-xSx. In this paper, we aim to provide a comprehensive summary of the preparation methods employed for 11 iron-based single crystals over the past decade. Specifically, we will focus on hydrothermal, chemical vapor transport (CVT), self-flux and annealing methods. Additionally, we will discuss the quality, size, and superconductivity properties exhibited by single crystals obtained through different preparation methods. By exploring these aspects, we can gain a better understanding of the advantages and limitations associated with each technique. High-quality single crystals serve as invaluable tools for advancing both the theoretical understanding and practical utilization of high-temperature superconductivity.
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Affiliation(s)
- Qiang Hou
- School of Physics, Southeast University, Nanjing 211189, China
| | - Longfei Sun
- School of Physics, Southeast University, Nanjing 211189, China
| | - Yue Sun
- School of Physics, Southeast University, Nanjing 211189, China
| | - Zhixiang Shi
- School of Physics, Southeast University, Nanjing 211189, China
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5
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Matsuura K, Roppongi M, Qiu M, Sheng Q, Cai Y, Yamakawa K, Guguchia Z, Day RP, Kojima KM, Damascelli A, Sugimura Y, Saito M, Takenaka T, Ishihara K, Mizukami Y, Hashimoto K, Gu Y, Guo S, Fu L, Zhang Z, Ning F, Zhao G, Dai G, Jin C, Beare JW, Luke GM, Uemura YJ, Shibauchi T. Two superconducting states with broken time-reversal symmetry in FeSe 1-xS x. Proc Natl Acad Sci U S A 2023; 120:e2208276120. [PMID: 37186859 PMCID: PMC10214191 DOI: 10.1073/pnas.2208276120] [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: 05/13/2022] [Accepted: 04/12/2023] [Indexed: 05/17/2023] Open
Abstract
Iron-chalcogenide superconductors FeSe1-xSx possess unique electronic properties such as nonmagnetic nematic order and its quantum critical point. The nature of superconductivity with such nematicity is important for understanding the mechanism of unconventional superconductivity. A recent theory suggested the possible emergence of a fundamentally new class of superconductivity with the so-called Bogoliubov Fermi surfaces (BFSs) in this system. However, such an ultranodal pair state requires broken time-reversal symmetry (TRS) in the superconducting state, which has not been observed experimentally. Here, we report muon spin relaxation (μSR) measurements in FeSe1-xSx superconductors for 0 ≤ x ≤ 0.22 covering both orthorhombic (nematic) and tetragonal phases. We find that the zero-field muon relaxation rate is enhanced below the superconducting transition temperature Tc for all compositions, indicating that the superconducting state breaks TRS both in the nematic and tetragonal phases. Moreover, the transverse-field μSR measurements reveal that the superfluid density shows an unexpected and substantial reduction in the tetragonal phase (x > 0.17). This implies that a significant fraction of electrons remain unpaired in the zero-temperature limit, which cannot be explained by the known unconventional superconducting states with point or line nodes. The TRS breaking and the suppressed superfluid density in the tetragonal phase, together with the reported enhanced zero-energy excitations, are consistent with the ultranodal pair state with BFSs. The present results reveal two different superconducting states with broken TRS separated by the nematic critical point in FeSe1-xSx, which calls for the theory of microscopic origins that account for the relation between nematicity and superconductivity.
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Affiliation(s)
- Kohei Matsuura
- Department of Advanced Materials Science, University of Tokyo, Kashiwa277-8561, Japan
| | - Masaki Roppongi
- Department of Advanced Materials Science, University of Tokyo, Kashiwa277-8561, Japan
| | - Mingwei Qiu
- Department of Advanced Materials Science, University of Tokyo, Kashiwa277-8561, Japan
| | - Qi Sheng
- Department of Physics, Columbia University, New York, NY10027
| | - Yipeng Cai
- Quantum Matter Institute, University of British Columbia, Vancouver, BCV6T 1Z4, Canada
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BCV6T 1Z1, Canada
| | | | - Zurab Guguchia
- Department of Physics, Columbia University, New York, NY10027
| | - Ryan P. Day
- Quantum Matter Institute, University of British Columbia, Vancouver, BCV6T 1Z4, Canada
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BCV6T 1Z1, Canada
| | - Kenji M. Kojima
- Quantum Matter Institute, University of British Columbia, Vancouver, BCV6T 1Z4, Canada
- Centre for Molecular and Materials Science, TRIUMF, Vancouver, BCV6T 2A3, Canada
| | - Andrea Damascelli
- Quantum Matter Institute, University of British Columbia, Vancouver, BCV6T 1Z4, Canada
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BCV6T 1Z1, Canada
| | - Yuichi Sugimura
- Department of Advanced Materials Science, University of Tokyo, Kashiwa277-8561, Japan
| | - Mikihiko Saito
- Department of Advanced Materials Science, University of Tokyo, Kashiwa277-8561, Japan
| | - Takaaki Takenaka
- Department of Advanced Materials Science, University of Tokyo, Kashiwa277-8561, Japan
| | - Kota Ishihara
- Department of Advanced Materials Science, University of Tokyo, Kashiwa277-8561, Japan
| | - Yuta Mizukami
- Department of Advanced Materials Science, University of Tokyo, Kashiwa277-8561, Japan
| | - Kenichiro Hashimoto
- Department of Advanced Materials Science, University of Tokyo, Kashiwa277-8561, Japan
| | - Yilun Gu
- Department of Physics, Zhejiang University, Hangzhou310027, China
| | - Shengli Guo
- Department of Physics, Zhejiang University, Hangzhou310027, China
| | - Licheng Fu
- Department of Physics, Zhejiang University, Hangzhou310027, China
| | - Zheneng Zhang
- Department of Physics, Zhejiang University, Hangzhou310027, China
| | - Fanlong Ning
- Department of Physics, Zhejiang University, Hangzhou310027, China
| | - Guoqiang Zhao
- Beijing National Laboratory for Condensed Matter Physics, Beijing100190, China
- Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
- University of Chinese Academy of Sciences, Beijing100190, China
| | - Guangyang Dai
- Beijing National Laboratory for Condensed Matter Physics, Beijing100190, China
- Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
- University of Chinese Academy of Sciences, Beijing100190, China
| | - Changqing Jin
- Beijing National Laboratory for Condensed Matter Physics, Beijing100190, China
- Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
- University of Chinese Academy of Sciences, Beijing100190, China
| | - James W. Beare
- Department of Physics and Astronomy, McMaster University, Hamilton, ONL8S 4M1, Canada
| | - Graeme M. Luke
- Centre for Molecular and Materials Science, TRIUMF, Vancouver, BCV6T 2A3, Canada
- Department of Physics and Astronomy, McMaster University, Hamilton, ONL8S 4M1, Canada
| | | | - Takasada Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Kashiwa277-8561, Japan
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6
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Wang A, Milosavljevic A, Abeykoon AMM, Ivanovski V, Du Q, Baum A, Stavitski E, Liu Y, Lazarevic N, Attenkofer K, Hackl R, Popovic Z, Petrovic C. Suppression of Superconductivity and Nematic Order in Fe 1-ySe 1-xS x (0 ≤ x ≤ 1; y ≤ 0.1) Crystals by Anion Height Disorder. Inorg Chem 2022; 61:11036-11045. [PMID: 35830279 DOI: 10.1021/acs.inorgchem.2c00568] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Connections between crystal chemistry and critical temperature Tc have been in the focus of superconductivity, one of the most widely studied phenomena in physics, chemistry, and materials science alike. In most Fe-based superconductors, materials chemistry and physics conspire so that Tc correlates with the average anion height above the Fe plane, i.e., with the geometry of the FeAs4 or FeCh4 (Ch = Te, Se, or S) tetrahedron. By synthesizing Fe1-ySe1-xSx (0 ≤ x ≤ 1; y ≤ 0.1), we find that in alloyed crystals Tc is not correlated with the anion height like it is for most other Fe superconductors. Instead, changes in Tc(x) and tetragonal-to-orthorhombic (nematic) transition Ts(x) upon cooling are correlated with disorder in Fe vibrations in the direction orthogonal to Fe planes, along the crystallographic c-axis. The disorder stems from the random nature of S substitution, causing deformed Fe(Se,S)4 tetrahedra with different Fe-Se and Fe-S bond distances. Our results provide evidence of Tc and Ts suppression by disorder in anion height. The connection to local crystal chemistry may be exploited in computational prediction of new superconducting materials with FeSe/S building blocks.
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Affiliation(s)
- Aifeng Wang
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Ana Milosavljevic
- Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - A M Milinda Abeykoon
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Valentin Ivanovski
- Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade 11001, Serbia
| | - Qianheng Du
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States.,Materials Science and Chemical Engineering Department, Stony Brook University, Stony Brook, New York 11790, United States
| | - Andreas Baum
- Walther Meissner Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.,Fakultät für Physik E23, Technische Universität München, 85748 Garching, Germany
| | - Eli Stavitski
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Yu Liu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Nenad Lazarevic
- Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Klaus Attenkofer
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Rudi Hackl
- Walther Meissner Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.,Fakultät für Physik E23, Technische Universität München, 85748 Garching, Germany
| | - Zoran Popovic
- Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia.,Serbian Academy of Sciences and Arts, Kneza Mihaila 35, Belgrade 11000, Serbia
| | - Cedomir Petrovic
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States.,Materials Science and Chemical Engineering Department, Stony Brook University, Stony Brook, New York 11790, United States
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7
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Abstract
SignificanceThe notion of the quantum critical point (QCP) is at the core of modern condensed matter physics. Near a QCP of the symmetry-breaking order, associated quantum-mechanical fluctuations are intensified, which can lead to unconventional superconductivity. Indeed, dome-shaped superconducting phases are often observed near the magnetic QCPs, which supports the spin fluctuation-driven superconductivity. However, the fundamental question remains as to whether a nonmagnetic QCP of electronic nematic order characterized by spontaneous rotational symmetry breaking can promote superconductivity in real materials. Here, we provide an experimental demonstration that a pure nematic QCP exists near the center of a superconducting dome in nonmagnetic FeSe[Formula: see text] Tex. This result evidences that nematic fluctuations enhanced around the nematic QCP can boost superconductivity.
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8
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Oh H, Agterberg DF, Moon EG. Using Disorder to Identify Bogoliubov Fermi-Surface States. PHYSICAL REVIEW LETTERS 2021; 127:257002. [PMID: 35029417 DOI: 10.1103/physrevlett.127.257002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 11/16/2021] [Indexed: 06/14/2023]
Abstract
We argue that a superconducting state with a Fermi surface of Bogoliubov quasiparticles, a Bogoliubov Fermi surface (BG-FS), can be identified by the dependence of physical quantities on disorder. In particular, we show that a linear dependence of the residual density of states at weak disorder distinguishes a BG-FS state from other nodal superconducting states. We further demonstrate the stability of supercurrent against impurities and a characteristic Drude-like behavior of the optical conductivity. Our results can be directly applied to electron irradiation experiments on candidate materials of BG-FSs, including Sr_{2}RuO_{4}, FeSe_{1-x}S_{x}, and UBe_{13}.
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Affiliation(s)
- Hanbit Oh
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
| | - Daniel F Agterberg
- Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53201, USA
| | - Eun-Gook Moon
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
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9
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Kasahara S, Suzuki H, Machida T, Sato Y, Ukai Y, Murayama H, Suetsugu S, Kasahara Y, Shibauchi T, Hanaguri T, Matsuda Y. Quasiparticle Nodal Plane in the Fulde-Ferrell-Larkin-Ovchinnikov State of FeSe. PHYSICAL REVIEW LETTERS 2021; 127:257001. [PMID: 35029441 DOI: 10.1103/physrevlett.127.257001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/16/2021] [Indexed: 06/14/2023]
Abstract
The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, characterized by Cooper pairs condensed at finite momentum, has been a long-sought state that remains unresolved in many classes of fermionic systems, including superconductors and ultracold atoms. A fascinating aspect of the FFLO state is the emergence of periodic nodal planes in real space, but its observation is still lacking. Here we investigate the superconducting order parameter at high magnetic fields H applied perpendicular to the ab plane in a high-purity single crystal of FeSe. The heat capacity and magnetic torque provide thermodynamic evidence for a distinct superconducting phase at the low-temperature/high-field corner of the phase diagram. Despite the bulk superconductivity, spectroscopic-imaging scanning tunneling microscopy performed on the same crystal demonstrates that the order parameter vanishes at the surface upon entering the high-field phase. These results provide the first demonstration of a pinned planar node perpendicular to H, which is consistent with a putative FFLO state.
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Affiliation(s)
- S Kasahara
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - H Suzuki
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - T Machida
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Y Sato
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Y Ukai
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - H Murayama
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - S Suetsugu
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Y Kasahara
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - T Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - T Hanaguri
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
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10
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Xie J, Liu X, Zhang W, Wong SM, Zhou X, Zhao Y, Wang S, Lai KT, Goh SK. Fragile Pressure-Induced Magnetism in FeSe Superconductors with a Thickness Reduction. NANO LETTERS 2021; 21:9310-9317. [PMID: 34714653 DOI: 10.1021/acs.nanolett.1c03508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The emergence of high transition temperature (Tc) superconductivity in bulk FeSe under pressure is associated with the tuning of nematicity and magnetism. However, sorting out the relative contributions from magnetic and nematic fluctuations to the enhancement of Tc remains challenging. Here, we design and conduct a series of high-pressure experiments on FeSe thin flakes. We find that as the thickness decreases the nematic phase boundary on temperature-pressure phase diagrams remains robust while the magnetic order is significantly weakened. A local maximum of Tc is observed outside the nematic phase region, not far from the extrapolated nematic end point in all samples. However, the maximum Tc value is reduced associated with the weakening of magnetism. No high-Tc phase is observed in the thinnest sample. Our results strongly suggest that nematic fluctuations alone can only have a limited effect while magnetic fluctuations are pivotal on the enhancement of Tc in FeSe.
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Affiliation(s)
- Jianyu Xie
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Xinyou Liu
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Wei Zhang
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Sum Ming Wong
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Xuefeng Zhou
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yusheng Zhao
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Shanmin Wang
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Kwing To Lai
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Swee K Goh
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
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11
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Hoshi K, Mizuguchi Y. Experimental overview on pairing mechanisms of BiCh 2-based (Ch: S, Se) layered superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:473001. [PMID: 34412049 DOI: 10.1088/1361-648x/ac1f4d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
BiCh2-based (Ch: S, Se) layered superconductors have attracted extensive attentions because of variation of materials and physical characteristics, which include relatively large spin-orbit coupling originating from bismuth 6porbitals, and the possibility of anisotropic superconducting gap. Some of theoretical studies suggested that anisotropic superconductivity is realized in the BiCh2-based superconductors. In experimental studies, angle-resolved photoemission spectroscopy measurement on the superconducting states of Nd(O,F)BiS2have revealed the anisotropic structure of the superconducting gap, and the absence of isotope effect have been reported, indicating unconventional superconductivity pairing. Furthermore, two-fold-symmetric in-plane anisotropy of magnetoresistance have been observed in the superconducting states of some of Bi(S,Se)2-based systems like La(O,F)Bi(S,Se)2while the crystal structure possesses a tetragonal square plane with four-fold symmetry. Those results indicate nematic superconductivity is emerging in BiCh2-based superconductors. On the basis of the observations suggesting unconventional superconductivity in BiCh2-based systems, clarification of pairing mechanisms of superconductivity in BiCh2-based superconductors have been highly desired. In this article, we review experimental results on the superconducting gap structure, the pairing mechanism, and related phenomena of BiCh2-based superconductors.
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Affiliation(s)
- Kazuhisa Hoshi
- Department of Physics, Tokyo Metropolitan University, 1-1, Minami-osawa, Hachioji 192-0397, Japan
| | - Yoshikazu Mizuguchi
- Department of Physics, Tokyo Metropolitan University, 1-1, Minami-osawa, Hachioji 192-0397, Japan
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12
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Shimojima T, Motoyui Y, Taniuchi T, Bareille C, Onari S, Kontani H, Nakajima M, Kasahara S, Shibauchi T, Matsuda Y, Shin S. Discovery of mesoscopic nematicity wave in iron-based superconductors. Science 2021; 373:1122-1125. [PMID: 34516833 DOI: 10.1126/science.abd6701] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- T Shimojima
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - Y Motoyui
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa 277-8581, Japan
| | - T Taniuchi
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa 277-8581, Japan.,Material Innovation Research Center (MIRC), The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - C Bareille
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa 277-8581, Japan.,Material Innovation Research Center (MIRC), The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - S Onari
- Department of Physics, Nagoya University, Furo-cho, Nagoya 464-8602, Japan
| | - H Kontani
- Department of Physics, Nagoya University, Furo-cho, Nagoya 464-8602, Japan
| | - M Nakajima
- Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - S Kasahara
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - T Shibauchi
- Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - S Shin
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa 277-8581, Japan.,Material Innovation Research Center (MIRC), The University of Tokyo, Kashiwa, Chiba 277-8561, Japan.,Office of University Professor, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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13
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Kuwayama T, Matsuura K, Gouchi J, Yamakawa Y, Mizukami Y, Kasahara S, Matsuda Y, Shibauchi T, Kontani H, Uwatoko Y, Fujiwara N. Pressure-induced reconstitution of Fermi surfaces and spin fluctuations in S-substituted FeSe. Sci Rep 2021; 11:17265. [PMID: 34446750 PMCID: PMC8390510 DOI: 10.1038/s41598-021-96277-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/04/2021] [Indexed: 11/19/2022] Open
Abstract
FeSe is a unique high-\documentclass[12pt]{minimal}
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\begin{document}$$T_c$$\end{document}Tc iron-based superconductor in which nematicity, superconductivity, and magnetism are entangled with each other in the P-T phase diagram. We performed \documentclass[12pt]{minimal}
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\begin{document}$$^{77}$$\end{document}77Se-nuclear magnetic resonance measurements under pressures of up to 3.9 GPa on 12% S-substituted FeSe, in which the complex overlap between the nematicity and magnetism are resolved. A pressure-induced Lifshitz transition was observed at 1.0 GPa as an anomaly of the density of states and as double superconducting (SC) domes accompanied by different types of antiferromagnetic (AF) fluctuations. The low-\documentclass[12pt]{minimal}
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\begin{document}$$T_{\mathrm{c}}$$\end{document}Tc SC dome below 1 GPa is accompanied by strong AF fluctuations, whereas the high-\documentclass[12pt]{minimal}
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\begin{document}$$T_{\mathrm{c}}$$\end{document}Tc SC dome develops above 1 GPa, where AF fluctuations are fairly weak. These results suggest the importance of the \documentclass[12pt]{minimal}
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\begin{document}$$d_{xy}$$\end{document}dxy orbital and its intra-orbital coupling for the high-\documentclass[12pt]{minimal}
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\begin{document}$$T_{\mathrm{c}}$$\end{document}Tc superconductivity.
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Affiliation(s)
- T Kuwayama
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-Nihonmatsu-cyo, Sakyo-ku, Kyoto, 606-8501, Japan
| | - K Matsuura
- Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581, Japan.,Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan
| | - J Gouchi
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581, Japan
| | - Y Yamakawa
- Department of Physics, Nagoya University, Furo-cho, Nagoya, 464-8602, Japan
| | - Y Mizukami
- Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581, Japan
| | - S Kasahara
- Division of Physics and Astronomy, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan.,Department of Physics, Okayama University, Okayama, 700-8530, Japan
| | - Y Matsuda
- Division of Physics and Astronomy, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - T Shibauchi
- Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581, Japan
| | - H Kontani
- Department of Physics, Nagoya University, Furo-cho, Nagoya, 464-8602, Japan
| | - Y Uwatoko
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581, Japan
| | - N Fujiwara
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-Nihonmatsu-cyo, Sakyo-ku, Kyoto, 606-8501, Japan.
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14
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High-pressure phase diagrams of FeSe 1-xTe x: correlation between suppressed nematicity and enhanced superconductivity. Nat Commun 2021; 12:381. [PMID: 33452257 PMCID: PMC7810696 DOI: 10.1038/s41467-020-20621-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 12/13/2020] [Indexed: 11/23/2022] Open
Abstract
The interplay among magnetism, electronic nematicity, and superconductivity is the key issue in strongly correlated materials including iron-based, cuprate, and heavy-fermion superconductors. Magnetic fluctuations have been widely discussed as a pairing mechanism of unconventional superconductivity, but recent theory predicts that quantum fluctuations of nematic order may also promote high-temperature superconductivity. This has been studied in FeSe1−xSx superconductors exhibiting nonmagnetic nematic and pressure-induced antiferromagnetic orders, but its abrupt suppression of superconductivity at the nematic end point leaves the nematic-fluctuation driven superconductivity unconfirmed. Here we report on systematic studies of high-pressure phase diagrams up to 8 GPa in high-quality single crystals of FeSe1−xTex. When Te composition x(Te) becomes larger than 0.1, the high-pressure magnetic order disappears, whereas the pressure-induced superconducting dome near the nematic end point is continuously found up to x(Te) ≈ 0.5. In contrast to FeSe1−xSx, enhanced superconductivity in FeSe1−xTex does not correlate with magnetism but with the suppression of nematicity, highlighting the paramount role of nonmagnetic nematic fluctuations for high-temperature superconductivity in this system. Despite studies in FeSe1−xSx, it is yet unconfirmed whether nematic fluctuation can induce superconductivity. Here, the authors study single crystals of FeSe1−xTex showing enhanced superconductivity upon suppression of nematicity.
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15
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Hashimoto T, Ota Y, Tsuzuki A, Nagashima T, Fukushima A, Kasahara S, Matsuda Y, Matsuura K, Mizukami Y, Shibauchi T, Shin S, Okazaki K. Bose-Einstein condensation superconductivity induced by disappearance of the nematic state. SCIENCE ADVANCES 2020; 6:6/45/eabb9052. [PMID: 33158862 PMCID: PMC7673702 DOI: 10.1126/sciadv.abb9052] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 09/24/2020] [Indexed: 06/11/2023]
Abstract
The crossover from the superconductivity of the Bardeen-Cooper-Schrieffer (BCS) regime to the Bose-Einstein condensation (BEC) regime holds a key to understanding the nature of pairing and condensation of fermions. It has been mainly studied in ultracold atoms, but in solid systems, fundamentally previously unknown insights may be obtained because multiple energy bands and coexisting electronic orders strongly affect spin and orbital degrees of freedom. Here, we provide evidence for the BCS-BEC crossover in iron-based superconductors FeSe1 - x S x from laser-excited angle-resolved photoemission spectroscopy. The system enters the BEC regime with x = 0.21, where the nematic state that breaks the orbital degeneracy is fully suppressed. The substitution dependence is opposite to the expectation for single-band superconductors, which calls for a new mechanism of BCS-BEC crossover in this system.
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Affiliation(s)
- Takahiro Hashimoto
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yuichi Ota
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Akihiro Tsuzuki
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Tsubaki Nagashima
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Akiko Fukushima
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | | | - Yuji Matsuda
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Kohei Matsuura
- Department of Advanced Materials Science, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Yuta Mizukami
- Department of Advanced Materials Science, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Takasada Shibauchi
- Department of Advanced Materials Science, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Shik Shin
- Office of University Professor, The University of Tokyo, Kashiwa, Chiba 277-8568, Japan
- Material Innovation Research Center, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Kozo Okazaki
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
- Material Innovation Research Center, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
- Trans-scale Quantum Science Institute, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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16
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Abstract
Emergent electronic phenomena in iron-based superconductors have been at the forefront of condensed matter physics for more than a decade. Much has been learned about the origins and intertwined roles of ordered phases, including nematicity, magnetism, and superconductivity, in this fascinating class of materials. In recent years, focus has been centered on the peculiar and highly unusual properties of FeSe and its close cousins. This family of materials has attracted considerable attention due to the discovery of unexpected superconducting gap structures, a wide range of superconducting critical temperatures, and evidence for nontrivial band topology, including associated spin-helical surface states and vortex-induced Majorana bound states. Here, we review superconductivity in iron chalcogenide superconductors, including bulk FeSe, doped bulk FeSe, FeTe1−xSex, intercalated FeSe materials, and monolayer FeSe and FeTe1−xSex on SrTiO3. We focus on the superconducting properties, including a survey of the relevant experimental studies, and a discussion of the different proposed theoretical pairing scenarios. In the last part of the paper, we review the growing recent evidence for nontrivial topological effects in FeSe-related materials, focusing again on interesting implications for superconductivity.
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17
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Kasahara S, Sato Y, Licciardello S, Čulo M, Arsenijević S, Ottenbros T, Tominaga T, Böker J, Eremin I, Shibauchi T, Wosnitza J, Hussey NE, Matsuda Y. Evidence for an Fulde-Ferrell-Larkin-Ovchinnikov State with Segmented Vortices in the BCS-BEC-Crossover Superconductor FeSe. PHYSICAL REVIEW LETTERS 2020; 124:107001. [PMID: 32216412 DOI: 10.1103/physrevlett.124.107001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 02/05/2020] [Indexed: 06/10/2023]
Abstract
We present resistivity and thermal-conductivity measurements of superconducting FeSe in intense magnetic fields up to 35 T applied parallel to the ab plane. At low temperatures, the upper critical field μ_{0}H_{c2}^{ab} shows an anomalous upturn, while thermal conductivity exhibits a discontinuous jump at μ_{0}H^{*}≈24 T well below μ_{0}H_{c2}^{ab}, indicating a first-order phase transition in the superconducting state. This demonstrates the emergence of a distinct field-induced superconducting phase. Moreover, the broad resistive transition at high temperatures abruptly becomes sharp upon entering the high-field phase, indicating a dramatic change of the magnetic-flux properties. We attribute the high-field phase to the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state, where the formation of planar nodes gives rise to a segmentation of the flux-line lattice. We point out that strongly orbital-dependent pairing as well as spin-orbit interactions, the multiband nature, and the extremely small Fermi energy are important for the formation of the FFLO state in FeSe.
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Affiliation(s)
- S Kasahara
- Department of Physics, Kyoto University, Kyoto 606-8502 Japan
| | - Y Sato
- Department of Physics, Kyoto University, Kyoto 606-8502 Japan
| | - S Licciardello
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
| | - M Čulo
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
| | - S Arsenijević
- Hochfeld-Magnetlabor Dresden (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, D-01328 Dresden, Germany
| | - T Ottenbros
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
| | - T Tominaga
- Department of Physics, Kyoto University, Kyoto 606-8502 Japan
| | - J Böker
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44801 Bochum, Germany
| | - I Eremin
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44801 Bochum, Germany
- National University of Science and Technology MISiS, 119049 Moscow, Russian Federation
| | - T Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - J Wosnitza
- Hochfeld-Magnetlabor Dresden (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, D-01328 Dresden, Germany
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
| | - N E Hussey
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
- H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, BS8 1TL, United Kingdom
| | - Y Matsuda
- Department of Physics, Kyoto University, Kyoto 606-8502 Japan
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18
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Topological ultranodal pair states in iron-based superconductors. Nat Commun 2020; 11:523. [PMID: 31988317 PMCID: PMC6985224 DOI: 10.1038/s41467-020-14357-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 12/19/2019] [Indexed: 11/09/2022] Open
Abstract
Bogoliubov Fermi surfaces are contours of zero-energy excitations that are protected in the superconducting state. Here we show that multiband superconductors with dominant spin singlet, intraband pairing of spin-1/2 electrons can undergo a transition to a state with Bogoliubov Fermi surfaces if spin-orbit coupling, interband pairing and time reversal symmetry breaking are also present. These latter effects may be small, but drive the transition to the topological state for appropriate nodal structure of the intra-band pair. Such a state should display nonzero zero-bias density of states and corresponding residual Sommerfeld coefficient as for a disordered nodal superconductor, but occurring even in the pure case. We present a model appropriate for iron-based superconductors where the topological transition associated with creation of a Bogoliubov Fermi surface can be studied. The model gives results that strongly resemble experiments on FeSe1−xSx across the nematic transition, where this ultranodal behavior may already have been observed. Experiments indicate an abrupt change in the pairing gap near the nematic transition in the FeSe1−xSx iron-based superconductor. Here, Setty et al. propose to explain them via a novel spin-1/2 paired state with topologically protected zero-energy excitations over a finite area nodal surface.
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19
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Romero AM, Ramos-Alonso L, Alepuz P, Puig S, Martínez-Pastor MT. Global translational repression induced by iron deficiency in yeast depends on the Gcn2/eIF2α pathway. Sci Rep 2020; 10:233. [PMID: 31937829 PMCID: PMC6959253 DOI: 10.1038/s41598-019-57132-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 12/16/2019] [Indexed: 11/09/2022] Open
Abstract
Iron is an essential element for all eukaryotic organisms because it participates as a redox active cofactor in a wide range of biological processes, including protein synthesis. Translation is probably the most energy consuming process in cells. Therefore, one of the initial responses of eukaryotic cells to stress or nutrient limitation is the arrest of mRNA translation. In first instance, the budding yeast Saccharomyces cerevisiae responds to iron deficiency by activating iron acquisition and remodeling cellular metabolism in order to prioritize essential over non-essential iron-dependent processes. We have determined that, despite a global decrease in transcription, mRNA translation is actively maintained during a short-term exposure to iron scarcity. However, a more severe iron deficiency condition induces a global repression of translation. Our results indicate that the Gcn2-eIF2α pathway limits general translation at its initiation step during iron deficiency. This bulk translational inhibition depends on the uncharged tRNA sensing Gcn1-Gcn20 complex. The involvement of the Gcn2-eIF2α pathway in the response to iron deficiency highlights its central role in the eukaryotic response to stress or nutritional deprivation, which is conserved from yeast to mammals.
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Affiliation(s)
- Antonia María Romero
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Catedrático Agustín Escardino 7, E-46980, Paterna, Valencia, Spain
| | - Lucía Ramos-Alonso
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Catedrático Agustín Escardino 7, E-46980, Paterna, Valencia, Spain
| | - Paula Alepuz
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, E-46100, Burjassot, Valencia, Spain.,ERI Biotecmed, Universitat de València, Doctor Moliner 50, E-46100, Burjassot, Valencia, Spain
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Catedrático Agustín Escardino 7, E-46980, Paterna, Valencia, Spain.
| | - María Teresa Martínez-Pastor
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, E-46100, Burjassot, Valencia, Spain.
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20
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Holenstein S, Stahl J, Shermadini Z, Simutis G, Grinenko V, Chareev DA, Khasanov R, Orain JC, Amato A, Klauss HH, Morenzoni E, Johrendt D, Luetkens H. Extended Magnetic Dome Induced by Low Pressures in Superconducting FeSe_{1-x}S_{x}. PHYSICAL REVIEW LETTERS 2019; 123:147001. [PMID: 31702214 DOI: 10.1103/physrevlett.123.147001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Indexed: 06/10/2023]
Abstract
We report muon spin rotation and magnetization measurements under pressure on Fe_{1+δ}Se_{1-x}S_{x} with x≈0.11. Above p≈0.6 GPa we find a microscopic coexistence of superconductivity with an extended dome of long range magnetic order that spans a pressure range between previously reported separated magnetic phases. The magnetism initially competes on an atomic scale with the coexisting superconductivity leading to a local maximum and minimum of the superconducting T_{c}(p). The maximum of T_{c} corresponds to the onset of magnetism while the minimum coincides with the pressure of strongest competition. A shift of the maximum of T_{c}(p) for a series of single crystals with x up to 0.14 roughly extrapolates to a putative magnetic and superconducting state at ambient pressure for x≥0.2.
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Affiliation(s)
- S Holenstein
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - J Stahl
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13 (D), 81377 München, Germany
| | - Z Shermadini
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - G Simutis
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - V Grinenko
- Institute of Solid State and Materials Physics, TU Dresden, DE-01069 Dresden, Germany
- Institute for Metallic Materials, Leibniz IFW Dresden, DE-01069 Dresden, Germany
| | - D A Chareev
- RAS, Institute of Experimental Mineralogy, Chernogolovka 123456, Russia
- Ural Federal University, Ekaterinburg 620002, Russia
- Kazan Federal University, Kazan 420008, Russia
| | - R Khasanov
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - J-C Orain
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - A Amato
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - H-H Klauss
- Institute of Solid State and Materials Physics, TU Dresden, DE-01069 Dresden, Germany
| | - E Morenzoni
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - D Johrendt
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13 (D), 81377 München, Germany
| | - H Luetkens
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
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21
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Shimizu M, Takemori N, Guterding D, Jeschke HO. Two-Dome Superconductivity in FeS Induced by a Lifshitz Transition. PHYSICAL REVIEW LETTERS 2018; 121:137001. [PMID: 30312064 DOI: 10.1103/physrevlett.121.137001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Indexed: 06/08/2023]
Abstract
Among iron chalcogenide superconductors, FeS can be viewed as a simple, highly compressed relative of FeSe without a nematic phase and with weaker electronic correlations. Under pressure, however, the superconductivity of stoichiometric FeS disappears and reappears, forming two domes. We perform electronic structure and spin fluctuation theory calculations for tetragonal FeS in order to analyze the nature of the superconducting order parameter. In the random phase approximation, we find a gap function with d-wave symmetry at ambient pressure, in agreement with several reports of a nodal superconducting order parameter in FeS. Our calculations show that, as a function of pressure, the superconducting pairing strength decreases until a Lifshitz transition takes place at 4.6 GPa. As a hole pocket with a large density of states appears at the Lifshitz transition, the gap symmetry is altered to sign-changing s wave. At the same time, the pairing strength is severely enhanced and increases up to a new maximum at 5.5 GPa. Therefore, our calculations naturally explain the occurrence of two superconducting domes in FeS.
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Affiliation(s)
- Makoto Shimizu
- Department of Physics, Okayama University, Okayama 700-8530, Japan
| | - Nayuta Takemori
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Daniel Guterding
- Fachbereich Mathematik, Naturwissenschaften und Datenverarbeitung, Technische Hochschule Mittelhessen, Wilhelm-Leuschner-Straße 13, 61169 Friedberg, Germany
| | - Harald O Jeschke
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
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22
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Kang J, Fernandes RM, Chubukov A. Superconductivity in FeSe: The Role of Nematic Order. PHYSICAL REVIEW LETTERS 2018; 120:267001. [PMID: 30004771 DOI: 10.1103/physrevlett.120.267001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Indexed: 06/08/2023]
Abstract
Bulk FeSe is a special iron-based material in which superconductivity emerges inside a well-developed nematic phase. We present a microscopic model for this nematic superconducting state, which takes into account the mixing between s-wave and d-wave pairing channels and the changes in the orbital spectral weight promoted by the sign-changing nematic order parameter. We show that nematicity only weakly affects T_{c}, but gives rise to cos2θ variation of the pairing gap on the hole pocket, whose magnitude and size agrees with angle resolved photoemission spectroscopy and STM data. We further show that nematicity increases the weight of the d_{xz} orbital on the hole pocket, and increases (reduces) the weight of the d_{xy} orbital on the Y (X) electron pocket.
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Affiliation(s)
- Jian Kang
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32304, USA
| | - Rafael M Fernandes
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Andrey Chubukov
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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23
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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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