1
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Ao L, Huang J, Qin F, Li Z, Ideue T, Akhtari K, Chen P, Bi X, Qiu C, Huang D, Chen L, Belosludov RV, Gou H, Ren W, Nojima T, Iwasa Y, Bahramy MS, Yuan H. Valley-dimensionality locking of superconductivity in cubic phosphides. SCIENCE ADVANCES 2023; 9:eadf6758. [PMID: 37683003 PMCID: PMC10491139 DOI: 10.1126/sciadv.adf6758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 08/08/2023] [Indexed: 09/10/2023]
Abstract
Two-dimensional superconductivity is primarily realized in atomically thin layers through extreme exfoliation, epitaxial growth, or interfacial gating. Apart from their technical challenges, these approaches lack sufficient control over the Fermiology of superconducting systems. Here, we offer a Fermiology-engineering approach, allowing us to desirably tune the coherence length of Cooper pairs and the dimensionality of superconducting states in arsenic phosphides AsxP1-x under hydrostatic pressure. We demonstrate how this turns these compounds into tunable two-dimensional superconductors with a dome-shaped phase diagram even in the bulk limit. This peculiar behavior is shown to result from an unconventional valley-dimensionality locking mechanism, driven by a delicate competition between three-dimensional hole-type and two-dimensional electron-type energy pockets spatially separated in momentum space. The resulting dimensionality crossover is further discussed to be systematically controllable by pressure and stoichiometry tuning. Our findings pave a unique way to realize and control superconducting phases with special pairing and dimensional orders.
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Affiliation(s)
- Lingyi Ao
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210000, China
| | - Junwei Huang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210000, China
| | - Feng Qin
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210000, China
| | - Zeya Li
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210000, China
| | - Toshiya Ideue
- Quantum-Phase Electronic Center and Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- Institute for Solid State Physics, The University of Tokyo, Chiba 277-8581, Japan
| | - Keivan Akhtari
- Department of Physics, University of Kurdistan, Sanandaj 416, Iran
| | - Peng Chen
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210000, China
| | - Xiangyu Bi
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210000, China
| | - Caiyu Qiu
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210000, China
| | - Dajian Huang
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China
| | - Long Chen
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | | | - Huiyang Gou
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China
| | - Wencai Ren
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Tsutomu Nojima
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Yoshihiro Iwasa
- Quantum-Phase Electronic Center and Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Mohammad Saeed Bahramy
- Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Hongtao Yuan
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210000, China
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2
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Song SY, Hua C, Bell L, Ko W, Fangohr H, Yan J, Halász GB, Dumitrescu EF, Lawrie BJ, Maksymovych P. Nematically Templated Vortex Lattices in Superconducting FeSe. NANO LETTERS 2023; 23:2822-2830. [PMID: 36940166 PMCID: PMC10103702 DOI: 10.1021/acs.nanolett.3c00125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/16/2023] [Indexed: 06/18/2023]
Abstract
New pathways to controlling the morphology of superconducting vortex lattices─and their subsequent dynamics─are required to guide and scale vortex world-lines into a computing platform. We have found that the nematic twin boundaries align superconducting vortices in the adjacent terraces due to the incommensurate potential between vortices surrounding twin boundaries and those trapped within them. With the varying density and morphology of twin boundaries, the vortex lattice assumes several distinct structural phases, including square, regular, and irregular one-dimensional lattices. Through concomitant analysis of vortex lattice models, we have inferred the characteristic energetics of the twin boundary potential and furthermore predicted the existence of geometric size effects as a function of increasing confinement by the twin boundaries. These findings extend the ideas of directed control over vortex lattices to intrinsic topological defects and their self-organized networks, which have direct implications for the future design and control of strain-based topological quantum computing architectures.
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Affiliation(s)
- Sang Yong Song
- Center
for Nanophase Materials Sciences, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Chengyun Hua
- Materials
Science and Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Luke Bell
- Department
of Physics, Yale University, New Haven, Connecticut 06520, United States
| | - Wonhee Ko
- Center
for Nanophase Materials Sciences, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department
of Physics and Astronomy, University of
Tennessee at Knoxville, Knoxville Tennessee 37996, United States
| | - Hans Fangohr
- Faculty
of Engineering and Physical Sciences, University
of Southampton, Southampton SO17 1BJ, U.K.
- Max Planck
Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Jiaqiang Yan
- Materials
Science and Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Gábor B. Halász
- Materials
Science and Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Eugene F. Dumitrescu
- Computational
Science and Engineering Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Benjamin J. Lawrie
- Materials
Science and Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Petro Maksymovych
- Center
for Nanophase Materials Sciences, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
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3
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Chen Z, Li D, Lu Z, Liu Y, Zhang J, Li Y, Yin R, Li M, Zhang T, Dong X, Yan YJ, Feng DL. Charge order driven by multiple-Q spin fluctuations in heavily electron-doped iron selenide superconductors. Nat Commun 2023; 14:2023. [PMID: 37041177 PMCID: PMC10090174 DOI: 10.1038/s41467-023-37792-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 03/28/2023] [Indexed: 04/13/2023] Open
Abstract
Intertwined spin and charge orders have been widely studied in high-temperature superconductors, since their fluctuations may facilitate electron pairing; however, they are rarely identified in heavily electron-doped iron selenides. Here, using scanning tunneling microscopy, we show that when the superconductivity of (Li0.84Fe0.16OH)Fe1-xSe is suppressed by introducing Fe-site defects, a short-ranged checkerboard charge order emerges, propagating along the Fe-Fe directions with an approximately 2aFe period. It persists throughout the whole phase space tuned by Fe-site defect density, from a defect-pinned local pattern in optimally doped samples to an extended order in samples with lower Tc or non-superconducting. Intriguingly, our simulations indicate that the charge order is likely driven by multiple-Q spin density waves originating from the spin fluctuations observed by inelastic neutron scattering. Our study proves the presence of a competing order in heavily electron-doped iron selenides, and demonstrates the potential of charge order as a tool to detect spin fluctuations.
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Affiliation(s)
- Ziyuan Chen
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Dong Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zouyouwei Lu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yue Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jiakang Zhang
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Yuanji Li
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Ruotong Yin
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Mingzhe Li
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Tong Zhang
- Department of Physics, State Key Laboratory of Surface Physics and Advanced Material Laboratory, Fudan University, Shanghai, 200438, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, China
- Shanghai Research Center for Quantum Sciences, Shanghai, 201315, China
| | - Xiaoli Dong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Ya-Jun Yan
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China.
| | - Dong-Lai Feng
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, China.
- Shanghai Research Center for Quantum Sciences, Shanghai, 201315, China.
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4
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Pandey S, Zhang H, Yang J, May AF, Sanchez JJ, Liu Z, Chu JH, Kim JW, Ryan PJ, Zhou H, Liu J. Controllable Emergent Spatial Spin Modulation in Sr_{2}IrO_{4} by In Situ Shear Strain. PHYSICAL REVIEW LETTERS 2022; 129:027203. [PMID: 35867461 DOI: 10.1103/physrevlett.129.027203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 06/15/2023]
Abstract
Symmetric anisotropic interaction can be ferromagnetic and antiferromagnetic at the same time but for different crystallographic axes. We show that the competition of anisotropic interactions of orthogonal irreducible representations can be a general route to obtain new exotic magnetic states. We demonstrate it here by observing the emergence of a continuously tunable 12-layer spatial spin modulation when distorting the square-lattice planes in the quasi-two-dimensional antiferromagnetic Sr_{2}IrO_{4} under in situ shear strain. This translation-symmetry-breaking phase is a result of an unusual strain-activated anisotropic interaction which is at the fourth order and competing with the inherent quadratic anisotropic interaction. Such a mechanism of competing anisotropy is distinct from that among the ferromagnetic, antiferromagnetic, and/or the Dzyaloshinskii-Moriya interactions, and it could be widely applicable and highly controllable in low-dimensional magnets.
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Affiliation(s)
- Shashi Pandey
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Han Zhang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Junyi Yang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Andrew F May
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Joshua J Sanchez
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Zhaoyu Liu
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Jiun-Haw Chu
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Jong-Woo Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Philip J Ryan
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
- School of Physical Sciences, Dublin City University, Dublin 11, Ireland
| | - Haidong Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Jian Liu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
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5
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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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6
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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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7
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Quadrupolar charge dynamics in the nonmagnetic FeSe 1-x S x superconductors. Proc Natl Acad Sci U S A 2021; 118:2020585118. [PMID: 33980712 DOI: 10.1073/pnas.2020585118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We use polarization-resolved electronic Raman spectroscopy to study quadrupolar charge dynamics in a nonmagnetic [Formula: see text] superconductor. We observe two types of long-wavelength [Formula: see text] symmetry excitations: 1) a low-energy quasi-elastic scattering peak (QEP) and 2) a broad electronic continuum with a maximum at 55 meV. Below the tetragonal-to-orthorhombic structural transition at [Formula: see text], a pseudogap suppression with temperature dependence reminiscent of the nematic order parameter develops in the [Formula: see text] symmetry spectra of the electronic excitation continuum. The QEP exhibits critical enhancement upon cooling toward [Formula: see text] The intensity of the QEP grows with increasing sulfur concentration x and maximizes near critical concentration [Formula: see text], while the pseudogap size decreases with the suppression of [Formula: see text] We interpret the development of the pseudogap in the quadrupole scattering channel as a manifestation of transition from the non-Fermi liquid regime, dominated by strong Pomeranchuk-like fluctuations giving rise to intense electronic continuum of excitations in the fourfold symmetric high-temperature phase, to the Fermi liquid regime in the broken-symmetry nematic phase where the quadrupole fluctuations are suppressed.
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8
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Kawashima T, Miyasaka S, Tsuji H, Yamamoto T, Uekubo M, Takemori A, Lai KT, Tajima S. Importance of [Formula: see text] orbital and electron correlation in iron-based superconductors revealed by phase diagram for 1111-system. Sci Rep 2021; 11:10006. [PMID: 33976326 PMCID: PMC8113352 DOI: 10.1038/s41598-021-89231-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 04/22/2021] [Indexed: 11/09/2022] Open
Abstract
The structural flexibility at three substitution sites in LaFeAsO enabled investigation of the relation between superconductivity and structural parameters over a wide range of crystal compositions. Substitutions of Nd for La, Sb or P for As, and F or H for O were performed. All these substitutions modify the local structural parameters, while the F/H-substitution also changes band filling. It was found that the superconducting transition temperature [Formula: see text] is strongly affected by the pnictogen height [Formula: see text] from the Fe-plane that controls the electron correlation strength and the size of the [Formula: see text] hole Fermi surface (FS). With increasing [Formula: see text], weak coupling BCS superconductivity switches to the strong coupling non-BCS one where electron correlations and the [Formula: see text] hole FS may be important.
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Affiliation(s)
- Tsuyoshi Kawashima
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 Japan
| | - Shigeki Miyasaka
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 Japan
| | - Hirokazu Tsuji
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 Japan
| | - Takahiro Yamamoto
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 Japan
| | - Masahiro Uekubo
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 Japan
| | - Akira Takemori
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 Japan
| | - Kwing To Lai
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 Japan
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Setsuko Tajima
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 Japan
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9
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Incommensurate smectic phase in close proximity to the high-T c superconductor FeSe/SrTiO 3. Nat Commun 2021; 12:2196. [PMID: 33850158 PMCID: PMC8044195 DOI: 10.1038/s41467-021-22516-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 03/18/2021] [Indexed: 11/23/2022] Open
Abstract
Superconductivity is significantly enhanced in monolayer FeSe grown on SrTiO3, but not for multilayer films, in which large strength of nematicity develops. However, the link between the high-transition temperature superconductivity in monolayer and the correlation related nematicity in multilayer FeSe films is not well understood. Here, we use low-temperature scanning tunneling microscopy to study few-layer FeSe thin films grown by molecular beam epitaxy. We observe an incommensurate long-range smectic phase, which solely appears in bilayer FeSe films. The smectic order still locally exists and gradually fades away with increasing film thickness, while it suddenly vanishes in monolayer FeSe, indicative of an abrupt smectic phase transition. Surface alkali-metal doping can suppress the smectic phase and induce high-Tc superconductivity in bilayer FeSe. Our observations provide evidence that the monolayer FeSe is in close proximity to the smectic phase, and its superconductivity is likely enhanced by this electronic instability as well. The relation between enhanced superconductivity in monolayer FeSe grown on SrTiO3 and the large nematicity in multilayer FeSe on SrTiO3 remains not well understood. Here, the authors observe a long-range smectic phase in bilayer FeSe films but vanishes in monolayer FeSe, providing a new instability to help enhance the superconductivity.
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10
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Wu S, Song Y, He Y, Frano A, Yi M, Chen X, Uchiyama H, Alatas A, Said AH, Wang L, Wolf T, Meingast C, Birgeneau RJ. Short-Range Nematic Fluctuations in Sr_{1-x}Na_{x}Fe_{2}As_{2} Superconductors. PHYSICAL REVIEW LETTERS 2021; 126:107001. [PMID: 33784111 DOI: 10.1103/physrevlett.126.107001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 02/02/2021] [Indexed: 06/12/2023]
Abstract
Interactions between nematic fluctuations, magnetic order and superconductivity are central to the physics of iron-based superconductors. Here we report on in-plane transverse acoustic phonons in hole-doped Sr_{1-x}Na_{x}Fe_{2}As_{2} measured via inelastic x-ray scattering, and extract both the nematic susceptibility and the nematic correlation length. By a self-contained method of analysis, for the underdoped (x=0.36) sample, which harbors a magnetically ordered tetragonal phase, we find it hosts a short nematic correlation length ξ∼10 Å and a large nematic susceptibility χ_{nem}. The optimal-doped (x=0.55) sample exhibits weaker phonon softening effects, indicative of both reduced ξ and χ_{nem}. Our results suggest short-range nematic fluctuations may favor superconductivity, placing emphasis on the nematic correlation length for understanding the iron-based superconductors.
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Affiliation(s)
- Shan Wu
- Department of Physics, University of California, Berkeley, California 94720, USA
- Material Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
| | - Yu Song
- Department of Physics, University of California, Berkeley, California 94720, USA
- Material Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
| | - Yu He
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Alex Frano
- Department of Physics, University of California, San Diego, California 92093, USA
| | - Ming Yi
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Xiang Chen
- Department of Physics, University of California, Berkeley, California 94720, USA
- Material Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
| | - Hiroshi Uchiyama
- Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Ahmet Alatas
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Ayman H Said
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Liran Wang
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Thomas Wolf
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Christoph Meingast
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Robert J Birgeneau
- Department of Physics, University of California, Berkeley, California 94720, USA
- Material Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
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11
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Ren Z, Li H, Zhao H, Sharma S, Wang Z, Zeljkovic I. Nanoscale decoupling of electronic nematicity and structural anisotropy in FeSe thin films. Nat Commun 2021; 12:10. [PMID: 33397896 PMCID: PMC7782804 DOI: 10.1038/s41467-020-20150-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 11/18/2020] [Indexed: 11/09/2022] Open
Abstract
In a material prone to a nematic instability, anisotropic strain in principle provides a preferred symmetry-breaking direction for the electronic nematic state to follow. This is consistent with experimental observations, where electronic nematicity and structural anisotropy typically appear hand-in-hand. In this work, we discover that electronic nematicity can be locally decoupled from the underlying structural anisotropy in strain-engineered iron-selenide (FeSe) thin films. We use heteroepitaxial molecular beam epitaxy to grow FeSe with a nanoscale network of modulations that give rise to spatially varying strain. We map local anisotropic strain by analyzing scanning tunneling microscopy topographs, and visualize electronic nematic domains from concomitant spectroscopic maps. While the domains form so that the energy of nemato-elastic coupling is minimized, we observe distinct regions where electronic nematic ordering fails to flip direction, even though the underlying structural anisotropy is locally reversed. The findings point towards a nanometer-scale stiffness of the nematic order parameter.
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Affiliation(s)
- Zheng Ren
- Department of Physics, Boston College, 140 Commonwealth Ave, Chestnut Hill, MA, 02467, USA
| | - Hong Li
- Department of Physics, Boston College, 140 Commonwealth Ave, Chestnut Hill, MA, 02467, USA
| | - He Zhao
- Department of Physics, Boston College, 140 Commonwealth Ave, Chestnut Hill, MA, 02467, USA
| | - Shrinkhala Sharma
- Department of Physics, Boston College, 140 Commonwealth Ave, Chestnut Hill, MA, 02467, USA
| | - Ziqiang Wang
- Department of Physics, Boston College, 140 Commonwealth Ave, Chestnut Hill, MA, 02467, USA
| | - Ilija Zeljkovic
- Department of Physics, Boston College, 140 Commonwealth Ave, Chestnut Hill, MA, 02467, USA.
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12
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Le T, Sun Y, Jin HK, Che L, Yin L, Li J, Pang G, Xu C, Zhao L, Kittaka S, Sakakibara T, Machida K, Sankar R, Yuan H, Chen G, Xu X, Li S, Zhou Y, Lu X. Evidence for nematic superconductivity of topological surface states in PbTaSe 2. Sci Bull (Beijing) 2020; 65:1349-1355. [PMID: 36659213 DOI: 10.1016/j.scib.2020.04.039] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 03/27/2020] [Accepted: 04/23/2020] [Indexed: 01/21/2023]
Abstract
Spontaneous symmetry breaking has been a paradigm to describe the phase transitions in condensed matter physics. In addition to the continuous electromagnetic gauge symmetry, an unconventional superconductor can break discrete symmetries simultaneously, such as time reversal and lattice rotational symmetry. In this work we report a characteristic in-plane 2-fold behaviour of the resistive upper critical field and point-contact spectra on the superconducting semimetal PbTaSe2 with topological nodal-rings, despite its hexagonal lattice symmetry (or D3h in bulk while C3v on surface, to be precise). The 2-fold behaviour persists up to its surface upper critical field Hc2R even though bulk superconductivity has been suppressed at its bulk upper critical field Hc2HC≪Hc2R, signaling its probable surface-only electronic nematicity. In addition, we do not observe any lattice rotational symmetry breaking signal from field-angle-dependent specific heat within the resolution. It is worth noting that such surface-only electronic nematicity is in sharp contrast to the observation in the topological superconductor candidate, CuxBi2Se3, where the nematicity occurs in various bulk measurements. In combination with theory, superconducting nematicity is likely to emerge from the topological surface states of PbTaSe2, rather than the proximity effect. The issue of time reversal symmetry breaking is also addressed. Thus, our results on PbTaSe2 shed new light on possible routes to realize nematic superconductivity with nontrivial topology.
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Affiliation(s)
- Tian Le
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - Yue Sun
- Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara 252-5258, Japan.
| | - Hui-Ke Jin
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Liqiang Che
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - Lichang Yin
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - Jie Li
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - Guiming Pang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - Chunqiang Xu
- Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China
| | - Lingxiao Zhao
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Shunichiro Kittaka
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Toshiro Sakakibara
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Kazushige Machida
- Department of Physics, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Raman Sankar
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan, China
| | - Huiqiu Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China; Zhejiang Province Key Laboratory of Quantum Technology and Device, Zhejiang University, Hangzhou 310027, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Genfu Chen
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Xiaofeng Xu
- Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China.
| | - Shiyan Li
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yi Zhou
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China; Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Xin Lu
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China; Zhejiang Province Key Laboratory of Quantum Technology and Device, Zhejiang University, Hangzhou 310027, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
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13
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Abstract
We have measured the angle-resolved transverse resistivity (ARTR), a sensitive indicator of electronic anisotropy, in high-quality thin films of the unconventional superconductor Sr2RuO4 grown on various substrates. The ARTR signal, heralding the electronic nematicity or a large nematic susceptibility, is present and substantial already at room temperature and grows by an order of magnitude upon cooling down to 4 K. In Sr2RuO4 films deposited on tetragonal substrates the highest-conductivity direction does not coincide with any crystallographic axis. In films deposited on orthorhombic substrates it tends to align with the shorter axis; however, the magnitude of the anisotropy stays the same despite the large lattice distortion. These are strong indications of actual or incipient electronic nematicity in Sr2RuO4.
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14
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Abstract
A nanoscale membrane enables exploration of large tensile strains on complex oxides
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Affiliation(s)
- Christianne Beekman
- Department of Physics, Florida State University, and National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA.
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15
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Novel electronic nematicity in heavily hole-doped iron pnictide superconductors. Proc Natl Acad Sci U S A 2020; 117:6424-6429. [PMID: 32165540 DOI: 10.1073/pnas.1909172117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Electronic nematicity, a correlated state that spontaneously breaks rotational symmetry, is observed in several layered quantum materials. In contrast to their liquid-crystal counterparts, the nematic director cannot usually point in an arbitrary direction (XY nematics), but is locked by the crystal to discrete directions (Ising nematics), resulting in strongly anisotropic fluctuations above the transition. Here, we report on the observation of nearly isotropic XY-nematic fluctuations, via elastoresistance measurements, in hole-doped Ba1-x Rb x Fe2As2 iron-based superconductors. While for [Formula: see text], the nematic director points along the in-plane diagonals of the tetragonal lattice, for [Formula: see text], it points along the horizontal and vertical axes. Remarkably, for intermediate doping, the susceptibilities of these two symmetry-irreducible nematic channels display comparable Curie-Weiss behavior, thus revealing a nearly XY-nematic state. This opens a route to assess this elusive electronic quantum liquid-crystalline state.
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16
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Kaneko UF, Piva MM, Jesus CBR, Saleta ME, Urbano RR, Pagliuso PG, Granado E. Evidence of precursor orthorhombic domains well above the electronic nematic transition temperature in Sr(Fe 1-x Co x ) 2As 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:495402. [PMID: 31284273 DOI: 10.1088/1361-648x/ab2ffc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Raman scattering, synchrotron x-ray diffraction, specific heat, resistivity and magnetic susceptibility measurements were performed in Sr(Fe1-x Co x )2As2 [[Formula: see text]] single crystals with superconducting critical temperature [Formula: see text] K and two additional transitions at 132 and 152 K observed in both specific heat and resistivity data. A quasielastic Raman signal with B 2g symmetry (tetragonal cell) associated with electronic nematic fluctuations is observed. Crucially, this signal shows maximum intensity at [Formula: see text] K, marking the nematic transition temperature. X-ray diffraction shows evidence of coexisting orthorhombic and tetragonal domains between [Formula: see text] and [Formula: see text] ∼ 152 K, implying that precursor orthorhombic domains emerge over an extended temperature range above [Formula: see text]. While the height of the quasielastic Raman peak is insensitive to [Formula: see text], the temperature-dependence of the average nematic fluctuation rate indicates a slowing down of the nematic fluctuations inside the precursor orthorhombic domains. These results are analogous to those previously reported for the LaFeAsO parent oxypnictide (Kaneko et al 2017 Phys. Rev. B 96 014506). We propose a scenario where the precursor orthorhombic phase may be generated within the electronically disordered regime ([Formula: see text]) as long as the nematic fluctuation rate is sufficiently small in comparison to the optical phonon frequency range. In this regime, the local atomic structure responds adiabatically to the electronic nematic fluctuations, creating a net of orthorhombic clusters that, albeit dynamical for [Formula: see text], may be sufficiently dense to sustain long-range phase coherence in a diffraction process up to [Formula: see text].
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Affiliation(s)
- U F Kaneko
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo 13083-100, Brazil
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17
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Nagase T, Komatsu M, So YG, Ishida T, Yoshida H, Kawaguchi Y, Tanaka Y, Saitoh K, Ikarashi N, Kuwahara M, Nagao M. Smectic Liquid-Crystalline Structure of Skyrmions in Chiral Magnet Co_{8.5}Zn_{7.5}Mn_{4}(110) Thin Film. PHYSICAL REVIEW LETTERS 2019; 123:137203. [PMID: 31697552 DOI: 10.1103/physrevlett.123.137203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Indexed: 06/10/2023]
Abstract
The organizing of magnetic skyrmions shows several forms similar to atomic arrays of solid states. Using Lorentz transmission electron microscopy, we report the first direct observation of a stable liquid-crystalline structure of skyrmions in chiral magnet Co_{8.5}Zn_{7.5}Mn_{4}(110) thin film, caused by magnetic anisotropy and chiral surface twist. Elongated skyrmions are oriented and periodically arranged only in the ⟨110⟩ directions, whereas they exhibit short-range order along the ⟨001⟩ directions, indicating a smectic skyrmion state. In addition, skyrmions possess anisotropic interaction with an opposite sign depending on the crystal orientation, in contrast to existing isotropic interaction.
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Affiliation(s)
- T Nagase
- Department of Electrical, Electronic Engineering and Information Engineering, School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - M Komatsu
- Department of Materials Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
| | - Y G So
- Department of Materials Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
| | - T Ishida
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
| | - H Yoshida
- Department of Physics, Hokkaido University, Sapporo 060-0810, Japan
| | - Y Kawaguchi
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - Y Tanaka
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - K Saitoh
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
| | - N Ikarashi
- Center for Integrated Research of Future Electronics, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
- Department of Electronics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - M Kuwahara
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
| | - M Nagao
- Center for Integrated Research of Future Electronics, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
- Department of Electronics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
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18
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Bozin ES, Yin WG, Koch RJ, Abeykoon M, Hor YS, Zheng H, Lei HC, Petrovic C, Mitchell JF, Billinge SJL. Local orbital degeneracy lifting as a precursor to an orbital-selective Peierls transition. Nat Commun 2019; 10:3638. [PMID: 31409783 PMCID: PMC6692321 DOI: 10.1038/s41467-019-11372-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 07/09/2019] [Indexed: 11/25/2022] Open
Abstract
Fundamental electronic principles underlying all transition metal compounds are the symmetry and filling of the d-electron orbitals and the influence of this filling on structural configurations and responses. Here we use a sensitive local structural technique, x-ray atomic pair distribution function analysis, to reveal the presence of fluctuating local-structural distortions at high temperature in one such compound, CuIr2S4. We show that this hitherto overlooked fluctuating symmetry-lowering is electronic in origin and will modify the energy-level spectrum and electronic and magnetic properties. The explanation is a local, fluctuating, orbital-degeneracy-lifted state. The natural extension of our result would be that this phenomenon is likely to be widespread amongst diverse classes of partially filled nominally degenerate d-electron systems, with potentially broad implications for our understanding of their properties. A common feature of many transition metal materials is global symmetry breaking at low temperatures. Here the authors show that such materials are characterized by fluctuating symmetry-lowering distortions that exist pre-formed in higher temperature phases with greater average symmetry.
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Affiliation(s)
- E S Bozin
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.
| | - W G Yin
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - R J Koch
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - M Abeykoon
- Photon Sciences Division, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Y S Hor
- Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA.,Department of Physics, Missouri University of Science and Technology, Rolla, MO, 65409, USA
| | - H Zheng
- Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - H C Lei
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.,Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, 100872, Beijing, China
| | - C Petrovic
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - J F Mitchell
- Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - S J L Billinge
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA. .,Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, 10027, USA.
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19
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Murayama H, Sato Y, Kurihara R, Kasahara S, Mizukami Y, Kasahara Y, Uchiyama H, Yamamoto A, Moon EG, Cai J, Freyermuth J, Greven M, Shibauchi T, Matsuda Y. Diagonal nematicity in the pseudogap phase of HgBa 2CuO 4+δ. Nat Commun 2019; 10:3282. [PMID: 31337758 PMCID: PMC6650423 DOI: 10.1038/s41467-019-11200-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 06/27/2019] [Indexed: 11/09/2022] Open
Abstract
The pseudogap phenomenon in the cuprates is arguably the most mysterious puzzle in the field of high-temperature superconductivity. The tetragonal cuprate HgBa2CuO4+δ, with only one CuO2 layer per primitive cell, is an ideal system to tackle this puzzle. Here, we measure the magnetic susceptibility anisotropy within the CuO2 plane with exceptionally high-precision magnetic torque experiments. Our key finding is that a distinct two-fold in-plane anisotropy sets in below the pseudogap temperature T*, which provides thermodynamic evidence for a nematic phase transition with broken four-fold symmetry. Surprisingly, the nematic director orients along the diagonal direction of the CuO2 square lattice, in sharp contrast to the bond nematicity along the Cu-O-Cu direction. Another remarkable feature is that the enhancement of the diagonal nematicity with decreasing temperature is suppressed around the temperature at which short-range charge-density-wave formation occurs. Our result suggests a competing relationship between diagonal nematic and charge-density-wave order in HgBa2CuO4+δ.
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Affiliation(s)
- H Murayama
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - Y Sato
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - R Kurihara
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - S Kasahara
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - Y Mizukami
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - Y Kasahara
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - H Uchiyama
- Materials Dynamics Laboratory, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan.,Research and Utilization Division, Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), 1-1-1 Kouto, Sayo, Hyogo, 679-5198, Japan
| | - A Yamamoto
- Graduate School of Engineering and Science, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo, 135-8584, Japan
| | - E-G Moon
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, 305-701, Korea
| | - J Cai
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.,Physics Department, University of Maryland, College Park, MD, 20742-4111, USA
| | - J Freyermuth
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.,Department of Physics, The Ohio State University, Columbus, OH, 43210-1117, USA
| | - M Greven
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - T Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan.
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20
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Sun Y, Kittaka S, Sakakibara T, Machida K, Wang J, Wen J, Xing X, Shi Z, Tamegai T. Quasiparticle Evidence for the Nematic State above T_{c} in Sr_{x}Bi_{2}Se_{3}. PHYSICAL REVIEW LETTERS 2019; 123:027002. [PMID: 31386520 DOI: 10.1103/physrevlett.123.027002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Indexed: 06/10/2023]
Abstract
In the electronic nematic state, an electronic system has a lower symmetry than the crystal structure of the same system. Electronic nematic states have been observed in various unconventional superconductors such as cuprate, iron-based, heavy-fermion, and topological superconductors. The relation between nematicity and superconductivity is a major unsolved problem in condensed matter physics. By angle-resolved specific heat measurements, we report bulk quasiparticle evidence of nematicity in the topological superconductor Sr_{x}Bi_{2}Se_{3}. The specific heat exhibited a clear twofold symmetry despite the threefold symmetric lattice. Most importantly, the twofold symmetry appeared in the normal state above the superconducting transition temperature. This is explained by the angle-dependent Zeeman effect due to the anisotropic density of states in the nematic phase. Such results highlight the interrelation between nematicity and unconventional superconductivity.
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Affiliation(s)
- Yue Sun
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara 252-5258, Japan
| | - Shunichiro Kittaka
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Toshiro Sakakibara
- Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Kazushige Machida
- Department of Physics, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Jinghui Wang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Jinsheng Wen
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Xiangzhuo Xing
- School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China
| | - Zhixiang Shi
- School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China
| | - Tsuyoshi Tamegai
- Department of Applied Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
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21
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Shimura Y, Zhang Q, Zeng B, Rhodes D, Schönemann R, Tsujimoto M, Matsumoto Y, Sakai A, Sakakibara T, Araki K, Zheng W, Zhou Q, Balicas L, Nakatsuji S. Giant Anisotropic Magnetoresistance due to Purely Orbital Rearrangement in the Quadrupolar Heavy Fermion Superconductor PrV_{2}Al_{20}. PHYSICAL REVIEW LETTERS 2019; 122:256601. [PMID: 31347904 DOI: 10.1103/physrevlett.122.256601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Indexed: 06/10/2023]
Abstract
We report the discovery of giant and anisotropic magnetoresistance due to the orbital rearrangement in a non magnetic correlated metal. In particular, we measured the magnetoresistance under fields up to 31.4 T in the cubic Pr-based heavy fermion superconductor PrV_{2}Al_{20} with a non magnetic Γ_{3} doublet ground state, exhibiting antiferroquadrupole ordering below 0.7 K. For the [100] direction, we find that the high-field phase appears between 12 and 25 T, accompanied by a large jump at 12 T in the magnetoresistance (ΔMR∼100%) and in the anisotropic magnetoresistivity ratio by ∼20%. These observations indicate that the strong hybridization between the conduction electrons and anisotropic quadrupole moments leads to the Fermi surface reconstruction upon crossing the field-induced antiferroquadrupole (orbital) rearrangement.
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Affiliation(s)
- Yasuyuki Shimura
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Qiu Zhang
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Bin Zeng
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Daniel Rhodes
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Rico Schönemann
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Masaki Tsujimoto
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yosuke Matsumoto
- Department of Quantum Materials, Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
| | - Akito Sakai
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Toshiro Sakakibara
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Koji Araki
- Department of Applied Physics, National Defense Academy, Yokosuka, Kanagawa 239-8686, Japan
| | - Wenkai Zheng
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Qiong Zhou
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Luis Balicas
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Satoru Nakatsuji
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
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22
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Hayami S, Yanagi Y, Kusunose H, Motome Y. Electric Toroidal Quadrupoles in the Spin-Orbit-Coupled Metal Cd_{2}Re_{2}O_{7}. PHYSICAL REVIEW LETTERS 2019; 122:147602. [PMID: 31050476 DOI: 10.1103/physrevlett.122.147602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Indexed: 06/09/2023]
Abstract
We report our theoretical results on the order parameters for the pyrochlore metal Cd_{2}Re_{2}O_{7}, which undergoes enigmatic phase transitions with inversion symmetry breaking. By carefully examining active electronic degrees of freedom based on the lattice symmetry, we propose that two parity-breaking phases at ambient pressure are described by unconventional multipoles, electric toroidal quadrupoles (ETQs) with different components, x^{2}-y^{2} and 3z^{2}-r^{2}, in the pyrochlore tetrahedral unit. We elucidate that the ETQs are activated by bond or spin-current order on Re─Re bonds. Our ETQ scenario provides a key to reconciling the experimental contradictions, by measuring ETQ specific phenomena, such as peculiar spin splittings in the electronic band structure, magnetocurrent effect, and nonreciprocal transport under a magnetic field.
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Affiliation(s)
- Satoru Hayami
- Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Yuki Yanagi
- Department of Physics, Meiji University, Kawasaki 214-8571, Japan
| | - Hiroaki Kusunose
- Department of Physics, Meiji University, Kawasaki 214-8571, Japan
| | - Yukitoshi Motome
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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23
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Yin X, Zhang C, Mu G, Hu T, Zhang M, Xiao H. Pressure tuning of iron-based superconductor Ca 10(Pt 3As 8) ((Fe 0.95Pt 0.05) 2As 2) 5. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:145601. [PMID: 30654354 DOI: 10.1088/1361-648x/aaffae] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Systematic high pressure transport measurements were performed on underdoped Ca10(Pt3As8)((Fe0.95Pt0.05)2As2)5 single crystal sample. At ambient pressure, the sample shows a metallic behavior at high temperatures and then increases with further decreasing temperature. The resistivity dip, which is associated with metal to semiconductor transition is monotonically suppressed by increasing pressure. In contrast, the superconducting transition temperature [Formula: see text] first increases with pressure and then decreases with further increasing pressure. Magnetization measurements, which gives the bulk [Formula: see text], show the same trend as the one obtained from resistivity measurements. An upward curvature is observed in the temperature dependence of the upper critical field [Formula: see text], which suggests the multiband nature of the superconductivity. The constructed temperature-pressure (T-P) phase diagram is very similar to the reported temperature-doping (T - x) phase diagram, suggesting the similar role played by pressure and chemical doping.
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Affiliation(s)
- X Yin
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China. School of Physics and Electronic Technology, Liaoning Normal University, Dalian 116029, People's Republic of China
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24
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Shiomi Y, Watanabe H, Masuda H, Takahashi H, Yanase Y, Ishiwata S. Observation of a Magnetopiezoelectric Effect in the Antiferromagnetic Metal EuMnBi_{2}. PHYSICAL REVIEW LETTERS 2019; 122:127207. [PMID: 30978058 DOI: 10.1103/physrevlett.122.127207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Indexed: 06/09/2023]
Abstract
We have experimentally studied a magnetopiezoelectric effect predicted recently for magnetic metals with low crystal symmetries. In EuMnBi_{2} with antiferromagnetic Mn moments at 77 K, dynamic displacements emerge along the a direction upon application of ac electric fields in the c direction and increase in proportion to the applied electric fields. Such displacements are not observed along the c direction of EuMnBi_{2} or EuZnBi_{2} with nonmagnetic Zn ions. As temperature increases from 77 K, the displacement signals decrease and disappear at about 200 K, above which electric conduction changes from coherent to incoherent. These results demonstrate the emergence of the magnetopiezoelectric effect in a magnetic metal lacking inversion and time-reversal symmetries.
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Affiliation(s)
- Y Shiomi
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Hongo, Tokyo 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Basic Science, University of Tokyo, Meguro, Tokyo 153-8902, Japan
| | - H Watanabe
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - H Masuda
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Hongo, Tokyo 113-8656, Japan
| | - H Takahashi
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Hongo, Tokyo 113-8656, Japan
| | - Y Yanase
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - S Ishiwata
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Hongo, Tokyo 113-8656, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
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25
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Liu X, Tao R, Ren M, Chen W, Yao Q, Wolf T, Yan Y, Zhang T, Feng D. Evidence of nematic order and nodal superconducting gap along [110] direction in RbFe 2As 2. Nat Commun 2019; 10:1039. [PMID: 30833562 PMCID: PMC6399313 DOI: 10.1038/s41467-019-08962-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 02/12/2019] [Indexed: 11/09/2022] Open
Abstract
Unconventional superconductivity often intertwines with various forms of order, such as the nematic order which breaks the rotational symmetry of the lattice. Here we report a scanning tunneling microscopy study on RbFe2As2, a heavily hole-doped Fe-based superconductor (FeSC). We observe significant symmetry breaking in its electronic structure and magnetic vortex which differentiates the (π, π) and (π, -π) directions of the unfolded Brillouin zone. It is thus a novel nematic state, distinct from the nematicity of undoped/lightly-doped FeSCs which breaks the (π, 0)/(0, π) equivalence. Moreover, we observe a clear V-shaped superconducting gap. The gap is suppressed on surface Rb vacancies and step edges, and the suppression is particularly strong at the [110]-oriented edges. This is possibly due to a \documentclass[12pt]{minimal}
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\begin{document}$${{d}}_{{{x}}^2 - {{y}}^2}$$\end{document}dx2-y2 like pairing component with nodes along the [110] directions. Our results thus highlight the intimate connection between nematicity and superconducting pairing in iron-based superconductors. Exotic electronic order may emerge and intertwine with superconductivity in iron-based superconductors. Here, the authors observe asymmetric electronic and superconducting gap structure in heavily hole-doped RbFe2As2 along the (π, π) and (π, -π) directions in reciprocal space, suggesting a novel (π, π) nematic phase emerging.
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Affiliation(s)
- Xi Liu
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Ran Tao
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Mingqiang Ren
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Wei Chen
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Qi Yao
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Thomas Wolf
- Institute for Solid State Physics, Karlsruhe Institute of Technology, D-76021, Karlsruhe, Germany
| | - Yajun Yan
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China
| | - Tong Zhang
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, China.
| | - Donglai Feng
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, 200433, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, China.
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26
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Lv Y, Dong Y, Lu D, Tian W, Xu Z, Chen W, Zhou X, Yuan J, Jin K, Bao S, Li S, Wen J, Chibotaru LF, Schwarz T, Kleiner R, Koelle D, Li J, Wang H, Wu P. Anomalous transverse resistance in 122-type iron-based superconductors. Sci Rep 2019; 9:664. [PMID: 30679657 PMCID: PMC6345833 DOI: 10.1038/s41598-018-37152-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 11/25/2018] [Indexed: 11/13/2022] Open
Abstract
The study of transverse resistance of superconductors is essential to understand the transition to superconductivity. Here, we investigated the in-plane transverse resistance of Ba0.5K0.5Fe2As2 superconductors, based on ultra-thin micro-bridges fabricated from optimally doped single crystals. An anomalous transverse resistance was found at temperatures around the superconducting transition, although magnetic order or structure distortion are absent in the optimal doping case. With the substitution of magnetic and nonmagnetic impurities into the superconducting layer, the anomalous transverse resistance phenomenon is dramatically enhanced. We find that anisotropic scattering or the superconducting electronic nematic state related with the superconducting transition may contribute to this phenomenon.
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Affiliation(s)
- Yangyang Lv
- Research Institute of Superconductor Electronics, Nanjing University, Nanjing, 210023, China
| | - Yu Dong
- Research Institute of Superconductor Electronics, Nanjing University, Nanjing, 210023, China
| | - Dachuan Lu
- Research Institute of Superconductor Electronics, Nanjing University, Nanjing, 210023, China
| | - Wanghao Tian
- Research Institute of Superconductor Electronics, Nanjing University, Nanjing, 210023, China
| | - Zuyu Xu
- Research Institute of Superconductor Electronics, Nanjing University, Nanjing, 210023, China
| | - Wei Chen
- Research Institute of Superconductor Electronics, Nanjing University, Nanjing, 210023, China
| | - Xianjing Zhou
- Research Institute of Superconductor Electronics, Nanjing University, Nanjing, 210023, China
| | - Jie Yuan
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.,Key Laboratory for Vacuum Physics, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kui Jin
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.,Key Laboratory for Vacuum Physics, University of Chinese Academy of Sciences, Beijing, 100049, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Song Bao
- School of Physics, Nanjing University, Nanjing, 210023, China.,National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Shichao Li
- School of Physics, Nanjing University, Nanjing, 210023, China.,National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Jinsheng Wen
- School of Physics, Nanjing University, Nanjing, 210023, China.,National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Liviu F Chibotaru
- Theory of Nanomaterials Group, KU Leuven, Celestijnenlaan 200F, Leuven, B-3001, Belgium
| | - Tobias Schwarz
- Physikalisches Institut-Experimentalphysik II and Center for Collective Quantum Phenomena in LISA, Universität Tübingen, Auf der Morgenstelle 14, Tübingen, D-72076, Germany
| | - Reinhold Kleiner
- Physikalisches Institut-Experimentalphysik II and Center for Collective Quantum Phenomena in LISA, Universität Tübingen, Auf der Morgenstelle 14, Tübingen, D-72076, Germany
| | - Dieter Koelle
- Physikalisches Institut-Experimentalphysik II and Center for Collective Quantum Phenomena in LISA, Universität Tübingen, Auf der Morgenstelle 14, Tübingen, D-72076, Germany
| | - Jun Li
- Research Institute of Superconductor Electronics, Nanjing University, Nanjing, 210023, China.
| | - Huabing Wang
- Research Institute of Superconductor Electronics, Nanjing University, Nanjing, 210023, China
| | - Peiheng Wu
- Research Institute of Superconductor Electronics, Nanjing University, Nanjing, 210023, China.,Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, Anhui, China
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27
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Abstract
Nematic superconductivity is a novel class of superconductivity characterized by spontaneous rotational-symmetry breaking in the superconducting gap amplitude and/or Cooper-pair spins with respect to the underlying lattice symmetry. Doped Bi 2 Se 3 superconductors, such as Cu x Bi 2 Se 3 , Sr x Bi 2 Se 3 , and Nb x Bi 2 Se 3 , are considered as candidates for nematic superconductors, in addition to the anticipated topological superconductivity. Recently, various bulk probes, such as nuclear magnetic resonance, specific heat, magnetotransport, magnetic torque, and magnetization, have consistently revealed two-fold symmetric behavior in their in-plane magnetic-field-direction dependence, although the underlying crystal lattice possesses three-fold rotational symmetry. More recently, nematic superconductivity was directly visualized using scanning tunneling microscopy and spectroscopy. In this short review, we summarize the current research on the nematic behavior in superconducting doped Bi 2 Se 3 systems and discuss issues and perspectives.
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28
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Yao DW, Li T. The driving mechanism of the d-wave orbital order in the iron-based superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:495601. [PMID: 30451156 DOI: 10.1088/1361-648x/aaec23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We study the driving mechanism and the form of the orbital order in the electronic nematic phase of the iron-based superconductors (IBSs) within the random phase approximation of a 5-band model. We find the magnetic correlation energy of the system can be significantly improved when an orbital order of the d-wave form is spontaneously generated. On the other hand, the magnetic correlation energy increases as one introduce either an on-site or an extended s-wave orbital order. More specifically, we find that the on-site orbital order is disfavored by the Hund's rule coupling and the extended s-wave orbital order is disfavored by the stripy magnetic correlation pattern in the IBSs. Our work indicates that the orbital order and the spin nematic order in the IBSs develop in a cooperative fashion in the electronic nematic phase of the IBSs and should be both understood as a component of a composite order.
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Affiliation(s)
- Da-Wei Yao
- Department of Physics, Renmin University of China, Beijing 100872, People's Republic of China
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29
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Yuan Y, Li W, Liu B, Deng P, Xu Z, Chen X, Song C, Wang L, He K, Xu G, Ma X, Xue QK. Edge States at Nematic Domain Walls in FeSe Films. NANO LETTERS 2018; 18:7176-7180. [PMID: 30350654 DOI: 10.1021/acs.nanolett.8b03282] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Quantum spin Hall (QSH) effect is an intriguing phenomenon arising from the helical edge states in two-dimensional topological insulators. We use molecular beam epitaxy (MBE) to prepare FeSe films with atomically sharp nematic domain boundaries, where tensile strains, nematicity suppression, and topological band inversion are simultaneously achieved. Using scanning tunneling microscopy (STM), we observe edge states at the Fermi level that spatially distribute as two distinct strips in the vicinity of the domain boundaries. At the end point of the boundaries, a bound state at the Fermi level is further observed. The topological origin of the edge states is supported by density functional theory calculations. Our findings not only demonstrate a candidate for QSH states but also provide a new pathway to realize topological superconductivity in a single-component film.
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Affiliation(s)
- Yonghao Yuan
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics , Tsinghua University , Beijing 100084 , China
| | - Wei Li
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics , Tsinghua University , Beijing 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
- Beijing Academy of Quantum Information Sciences , Beijing 100193 , China
| | - Bin Liu
- Wuhan National High Magnetic Field Center & School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Peng Deng
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics , Tsinghua University , Beijing 100084 , China
| | - Zhilin Xu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics , Tsinghua University , Beijing 100084 , China
| | - Xi Chen
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics , Tsinghua University , Beijing 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
| | - Canli Song
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics , Tsinghua University , Beijing 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics , Tsinghua University , Beijing 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
| | - Ke He
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics , Tsinghua University , Beijing 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
- Beijing Academy of Quantum Information Sciences , Beijing 100193 , China
| | - Gang Xu
- Wuhan National High Magnetic Field Center & School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Xucun Ma
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics , Tsinghua University , Beijing 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics , Tsinghua University , Beijing 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
- Beijing Academy of Quantum Information Sciences , Beijing 100193 , China
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30
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Wang W, Song Y, Cao C, Tseng KF, Keller T, Li Y, Harriger LW, Tian W, Chi S, Yu R, Nevidomskyy AH, Dai P. Local orthorhombic lattice distortions in the paramagnetic tetragonal phase of superconducting NaFe 1-xNi xAs. Nat Commun 2018; 9:3128. [PMID: 30087342 PMCID: PMC6081486 DOI: 10.1038/s41467-018-05529-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 07/13/2018] [Indexed: 11/08/2022] Open
Abstract
Understanding the interplay between nematicity, magnetism and superconductivity is pivotal for elucidating the physics of iron-based superconductors. Here we use neutron scattering to probe magnetic and nematic orders throughout the phase diagram of NaFe1-xNixAs, finding that while both static antiferromagnetic and nematic orders compete with superconductivity, the onset temperatures for these two orders remain well separated approaching the putative quantum critical points. We uncover local orthorhombic distortions that persist well above the tetragonal-to-orthorhombic structural transition temperature Ts in underdoped samples and extend well into the overdoped regime that exhibits neither magnetic nor structural phase transitions. These unexpected local orthorhombic distortions display Curie-Weiss temperature dependence and become suppressed below the superconducting transition temperature Tc, suggesting that they result from the large nematic susceptibility near optimal superconductivity. Our results account for observations of rotational symmetry breaking above Ts, and attest to the presence of significant nematic fluctuations near optimal superconductivity.
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Affiliation(s)
- Weiyi Wang
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Yu Song
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Chongde Cao
- Department of Applied Physics, Northwestern Polytechnical University, Xian, 710072, China.
| | - Kuo-Feng Tseng
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany
- Max Planck Society Outstation at the Forschungsneutronenquelle Heinz Maier-Leibnitz (MLZ), D-85747, Garching, Germany
| | - Thomas Keller
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany
- Max Planck Society Outstation at the Forschungsneutronenquelle Heinz Maier-Leibnitz (MLZ), D-85747, Garching, Germany
| | - Yu Li
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - L W Harriger
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Wei Tian
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Songxue Chi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Rong Yu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | | | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA.
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31
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Oropesa WGC, Correa VF, Sereni JG, García DJ, Cornaglia PS. Landau theory for magnetic and structural transitions in CeCo 0.85Fe 0.15Si. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:295803. [PMID: 29869989 DOI: 10.1088/1361-648x/aaca66] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present a phenomenological analysis of the magnetoelastic properties of CeCo0.85Fe0.15Si at temperatures close to the Néel transition temperature T N. Using a Landau functional we provide a qualitative description of the thermal expansion, magnetostriction, magnetization and specific heat data. We show that the available experimental results (Correa et al 2016 J. Phys.: Condens. Matter 28 346003) are consistent with the presence of a structural transition at [Formula: see text] and a strong magnetoelastic coupling. The magnetoelastic coupling presents a Janus-faced effect: while the structural transition is shifted to higher temperatures as the magnetic field is increased, the resulting striction at low temperatures decreases. The strong magnetoelastic coupling and the proximity of the structural transition to the onset temperature for magnetic fluctuations, suggest that the transition could be an analogue of the tetragonal to orthorhombic observed in Fe-based pcnictides.
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32
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Thewalt E, Hayes IM, Hinton JP, Little A, Patankar S, Wu L, Helm T, Stan CV, Tamura N, Analytis JG, Orenstein J. Imaging Anomalous Nematic Order and Strain in Optimally Doped BaFe_{2}(As,P)_{2}. PHYSICAL REVIEW LETTERS 2018; 121:027001. [PMID: 30085755 DOI: 10.1103/physrevlett.121.027001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Indexed: 06/08/2023]
Abstract
We present the strain and temperature dependence of an anomalous nematic phase in optimally doped BaFe_{2}(As,P)_{2}. Polarized ultrafast optical measurements reveal broken fourfold rotational symmetry in a temperature range above T_{c} in which bulk probes do not detect a phase transition. Using ultrafast microscopy, we find that the magnitude and sign of this nematicity vary on a 50-100 μm length scale, and the temperature at which it onsets ranges from 40 K near a domain boundary to 60 K deep within a domain. Scanning Laue microdiffraction maps of local strain at room temperature indicate that the nematic order appears most strongly in regions of weak, isotropic strain. These results indicate that nematic order arises in a genuine phase transition rather than by enhancement of local anisotropy by a strong nematic susceptibility. We interpret our results in the context of a proposed surface nematic phase.
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Affiliation(s)
- Eric Thewalt
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Ian M Hayes
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - James P Hinton
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Arielle Little
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Shreyas Patankar
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Liang Wu
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Toni Helm
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Camelia V Stan
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Nobumichi Tamura
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - James G Analytis
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Joseph Orenstein
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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33
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Yim CM, Trainer C, Aluru R, Chi S, Hardy WN, Liang R, Bonn D, Wahl P. Discovery of a strain-stabilised smectic electronic order in LiFeAs. Nat Commun 2018; 9:2602. [PMID: 29973598 PMCID: PMC6031620 DOI: 10.1038/s41467-018-04909-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 06/04/2018] [Indexed: 11/09/2022] Open
Abstract
In many high temperature superconductors, small orthorhombic distortions of the lattice structure result in surprisingly large symmetry breaking of the electronic states and macroscopic properties, an effect often referred to as nematicity. To directly study the impact of symmetry-breaking lattice distortions on the electronic states, using low-temperature scanning tunnelling microscopy we image at the atomic scale the influence of strain-tuned lattice distortions on the correlated electronic states in the iron-based superconductor LiFeAs, a material which in its ground state is tetragonal with four-fold (C4) symmetry. Our experiments uncover a new strain-stabilised modulated phase which exhibits a smectic order in LiFeAs, an electronic state which not only breaks rotational symmetry but also reduces translational symmetry. We follow the evolution of the superconducting gap from the unstrained material with C4 symmetry through the new smectic phase with two-fold (C2) symmetry and charge-density wave order to a state where superconductivity is completely suppressed.
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Affiliation(s)
- Chi Ming Yim
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - Christopher Trainer
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - Ramakrishna Aluru
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - Shun Chi
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Walter N Hardy
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Ruixing Liang
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Doug Bonn
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Peter Wahl
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK.
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34
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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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35
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Kalenyuk AA, Pagliero A, Borodianskyi EA, Kordyuk AA, Krasnov VM. Phase-Sensitive Evidence for the Sign-Reversal s_{±} Symmetry of the Order Parameter in an Iron-Pnictide Superconductor Using Nb/Ba_{1-x}Na_{x}Fe_{2}As_{2} Josephson Junctions. PHYSICAL REVIEW LETTERS 2018; 120:067001. [PMID: 29481253 DOI: 10.1103/physrevlett.120.067001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 12/18/2017] [Indexed: 06/08/2023]
Abstract
Josephson current provides a phase-sensitive tool for probing the pairing symmetry. Here we present an experimental study of high-quality Josephson junctions between a conventional s-wave superconductor Nb and a multiband iron-pnictide Ba_{1-x}Na_{x}Fe_{2}As_{2}. Junctions exhibit a large enough critical current density to preclude the d-wave symmetry of the order parameter in the pnictide. However, the I_{c}R_{n} product is very small ≃3μV, which is not consistent with the sign-preserving s_{++} symmetry either. We argue that the small I_{c}R_{n} value, along with its unusual temperature dependence, provides evidence for the sign-reversal s_{±} symmetry of the order parameter in Ba_{1-x}Na_{x}Fe_{2}As_{2}. We conclude that it is the phase sensitivity of our junctions that leads to an almost complete (below a subpercent) cancellation of supercurrents from sign-reversal bands in the pnictide.
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Affiliation(s)
- A A Kalenyuk
- Department of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
- Institute of Metal Physics of National Academy of Sciences of Ukraine, 03142 Kyiv, Ukraine
| | - A Pagliero
- Department of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
| | - E A Borodianskyi
- Department of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
| | - A A Kordyuk
- Institute of Metal Physics of National Academy of Sciences of Ukraine, 03142 Kyiv, Ukraine
- Kyiv Academic University, 03142 Kyiv, Ukraine
| | - V M Krasnov
- Department of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
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36
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Sonobe T, Shimojima T, Nakamura A, Nakajima M, Uchida S, Kihou K, Lee CH, Iyo A, Eisaki H, Ohgushi K, Ishizaka K. Orbital-anisotropic electronic structure in the nonmagnetic state of BaFe 2(As 1-xP x ) 2 superconductors. Sci Rep 2018; 8:2169. [PMID: 29391431 PMCID: PMC5794914 DOI: 10.1038/s41598-018-20332-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 01/16/2018] [Indexed: 12/02/2022] Open
Abstract
High-temperature superconductivity in iron-pnictides/chalcogenides arises in balance with several electronic and lattice instabilities. Beside the antiferromagnetic order, the orbital anisotropy between Fe 3d xz and 3d yz occurs near the orthorhombic structural transition in several parent compounds. However, the extent of the survival of orbital anisotropy against the ion-substitution remains to be established. Here we report the composition (x) and temperature (T) dependences of the orbital anisotropy in the electronic structure of a BaFe2(As1-xP x )2 system by using angle-resolved photoemission spectroscopy. In the low-x regime, the orbital anisotropy starts to evolve on cooling from high temperatures above both antiferromagnetic and orthorhombic transitions. By increasing x, it is gradually suppressed and survives in the optimally doped regime. We find that the in-plane orbital anisotropy persists in a large area of the nonmagnetic phase, including the superconducting dome. These results suggest that the rotational symmetry-broken electronic state acts as the stage for superconductivity in BaFe2(As1-xP x )2.
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Affiliation(s)
- T Sonobe
- Quantum-Phase Electronics Center (QPEC) and Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo, 113-8656, Japan
| | - T Shimojima
- Quantum-Phase Electronics Center (QPEC) and Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo, 113-8656, Japan.
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan.
| | - A Nakamura
- Quantum-Phase Electronics Center (QPEC) and Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo, 113-8656, Japan
| | - M Nakajima
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| | - S Uchida
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo, 113-0033, Japan
| | - K Kihou
- National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8568, Japan
| | - C H Lee
- National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8568, Japan
| | - A Iyo
- National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8568, Japan
| | - H Eisaki
- National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8568, Japan
| | - K Ohgushi
- Department of Physics, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - K Ishizaka
- Quantum-Phase Electronics Center (QPEC) and Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
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37
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Nakano K, Hongo K, Maezono R. Investigation into Structural Phase Transitions in Layered Titanium-Oxypnictides by a Computational Phonon Analysis. Inorg Chem 2017; 56:13732-13740. [PMID: 29094926 DOI: 10.1021/acs.inorgchem.7b01709] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We applied ab initio phonon analysis to layered titanium-oxypnictides, Na2Ti2Pn2O (Pn = As and Sb), and found a clear contrast between the cases with lighter/heavier pnictogen in comparison with experiments. The result completely explains the experimental structure at low temperature, C2/m for Pn = As, within the conventional charge density wave, while there arise discrepancies when the pnictogen gets heavier. Our phonon calculation using the GGA-PBE functional predicts that a Cmce polymorph is more stable than the experimentally observed one (Cmcm) for Pn = Sb. On the basis of further quantitative analysis, we suggest the possibility that the GGA-PBE functional does not properly reproduce the electron correlation effects for Pn = Sb, and this could be the reason for the present discrepancy.
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Affiliation(s)
- Kousuke Nakano
- School of Information Science, JAIST , Asahidai 1-1, Nomi, Ishikawa 923-1292, Japan
| | - Kenta Hongo
- Research Center for Advanced Computing Infrastructure, JAIST , Asahidai 1-1, Nomi, Ishikawa 923-1292, Japan.,PRESTO, Japan Science and Technology Agency (JST) , Kawaguchi, Saitama 332-0012, Japan.,Center for Materials Research by Information Integration, Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science , Tsukuba 305-0047, Japan
| | - Ryo Maezono
- School of Information Science, JAIST , Asahidai 1-1, Nomi, Ishikawa 923-1292, Japan
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38
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Frandsen BA, Taddei KM, Yi M, Frano A, Guguchia Z, Yu R, Si Q, Bugaris DE, Stadel R, Osborn R, Rosenkranz S, Chmaissem O, Birgeneau RJ. Local Orthorhombicity in the Magnetic C_{4} Phase of the Hole-Doped Iron-Arsenide Superconductor Sr_{1-x}Na_{x}Fe_{2}As_{2}. PHYSICAL REVIEW LETTERS 2017; 119:187001. [PMID: 29219610 DOI: 10.1103/physrevlett.119.187001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Indexed: 06/07/2023]
Abstract
We report on temperature-dependent pair distribution function measurements of Sr_{1-x}Na_{x}Fe_{2}As_{2}, an iron-based superconductor system that contains a magnetic phase with reentrant tetragonal symmetry, known as the magnetic C_{4} phase. Quantitative refinements indicate that the instantaneous local structure in the C_{4} phase comprises fluctuating orthorhombic regions with a length scale of ∼2 nm, despite the tetragonal symmetry of the average static structure. Additionally, local orthorhombic fluctuations exist on a similar length scale at temperatures well into the paramagnetic tetragonal phase. These results highlight the exceptionally large nematic susceptibility of iron-based superconductors and have significant implications for the magnetic C_{4} phase and the neighboring C_{2} and superconducting phases.
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Affiliation(s)
- Benjamin A Frandsen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Keith M Taddei
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Ming Yi
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Alex Frano
- Department of Physics, University of California, Berkeley, California 94720, USA
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Zurab Guguchia
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - Rong Yu
- Department of Physics, Renmin University of China, Beijing 100872, China
- Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qimiao Si
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Daniel E Bugaris
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Ryan Stadel
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Department of Physics, Northern Illinois University, DeKalb, Illinois 60439, USA
| | - Raymond Osborn
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Stephan Rosenkranz
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Omar Chmaissem
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Department of Physics, Northern Illinois University, DeKalb, Illinois 60439, USA
| | - Robert J Birgeneau
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California, Berkeley, California 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
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39
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Li T, Su Y. Driving force of the orbital-relevant electronic nematicity in Fe-based superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:425603. [PMID: 28805190 DOI: 10.1088/1361-648x/aa85f4] [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
The electronic nematic responses in Fe-based superconductors have been observed ubiquitously in various experimental probes. One novel nematic character is the d-wave bond orbital-relevant nematic charge order which was firstly proposed by symmetry analysis and then conformed by angle-resolved photoemission spectroscopy. In this paper, we present a mechanism that the driving force of the orbital-relevant nematic charge order is the reduction of the large Hubbard energy in the particle-hole charge channel by virtual hopping processes. This is one scenario from strong-coupling consideration. The same virtual hopping processes can lead to a super-exchange interaction for the spin magnetic order in the particle-hole spin channel and a pairing interaction for the superconducting order in the particle-particle channel. Thus the electronic nematic order, the spin magnetic order and the pairing superconducting order are intrinsically entangled and they can all stem from the same microscopic virtual hopping processes in reduction of the Hubbard energy. The electronic nematicity, the spin magnetism and the pairing superconductivity in unconventional superconductors are proposed to be unified within this mechanism.
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Affiliation(s)
- Tao Li
- Department of Physics, Renmin University of China, Beijing 100872, People's Republic of China
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40
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Dichotomy between in-plane magnetic susceptibility and resistivity anisotropies in extremely strained BaFe 2As 2. Nat Commun 2017; 8:504. [PMID: 28894127 PMCID: PMC5593886 DOI: 10.1038/s41467-017-00712-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 07/21/2017] [Indexed: 11/08/2022] Open
Abstract
High-temperature superconductivity in the Fe-based materials emerges when the antiferromagnetism of the parent compounds is suppressed by either doping or pressure. Closely connected to the antiferromagnetic state are entangled orbital, lattice, and nematic degrees of freedom, and one of the major goals in this field has been to determine the hierarchy of these interactions. Here we present the direct measurements and the calculations of the in-plane uniform magnetic susceptibility anisotropy of BaFe2As2, which help in determining the above hierarchy. The magnetization measurements are made possible by utilizing a simple method for applying a large symmetry-breaking strain, based on differential thermal expansion. In strong contrast to the large resistivity anisotropy above the antiferromagnetic transition at T N, the anisotropy of the in-plane magnetic susceptibility develops largely below T N. Our results imply that lattice and orbital degrees of freedom play a subdominant role in these materials.Interplay between lattice, orbital, magnetic and nematic degrees of freedom is crucial for the superconductivity in Fe-based materials. Here, the authors demonstrate the subdominant roles of pure lattice distortions and/or orbital ordering in BaFe2As2 by characterizing the in-plane magnetic susceptibility anisotropy.
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41
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Electronic in-plane symmetry breaking at field-tuned quantum criticality in CeRhIn 5. Nature 2017; 548:313-317. [PMID: 28783723 DOI: 10.1038/nature23315] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 06/14/2017] [Indexed: 11/08/2022]
Abstract
Electronic nematic materials are characterized by a lowered symmetry of the electronic system compared to the underlying lattice, in analogy to the directional alignment without translational order in nematic liquid crystals. Such nematic phases appear in the copper- and iron-based high-temperature superconductors, and their role in establishing superconductivity remains an open question. Nematicity may take an active part, cooperating or competing with superconductivity, or may appear accidentally in such systems. Here we present experimental evidence for a phase of fluctuating nematic character in a heavy-fermion superconductor, CeRhIn5 (ref. 5). We observe a magnetic-field-induced state in the vicinity of a field-tuned antiferromagnetic quantum critical point at Hc ≈ 50 tesla. This phase appears above an out-of-plane critical field H* ≈ 28 tesla and is characterized by a substantial in-plane resistivity anisotropy in the presence of a small in-plane field component. The in-plane symmetry breaking has little apparent connection to the underlying lattice, as evidenced by the small magnitude of the magnetostriction anomaly at H*. Furthermore, no anomalies appear in the magnetic torque, suggesting the absence of metamagnetism in this field range. The appearance of nematic behaviour in a prototypical heavy-fermion superconductor highlights the interrelation of nematicity and unconventional superconductivity, suggesting nematicity to be common among correlated materials.
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42
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Shimojima T, Malaeb W, Nakamura A, Kondo T, Kihou K, Lee CH, Iyo A, Eisaki H, Ishida S, Nakajima M, Uchida SI, Ohgushi K, Ishizaka K, Shin S. Antiferroic electronic structure in the nonmagnetic superconducting state of the iron-based superconductors. SCIENCE ADVANCES 2017; 3:e1700466. [PMID: 28875162 PMCID: PMC5573309 DOI: 10.1126/sciadv.1700466] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 08/01/2017] [Indexed: 06/07/2023]
Abstract
A major problem in the field of high-transition temperature (Tc) superconductivity is the identification of the electronic instabilities near superconductivity. It is known that the iron-based superconductors exhibit antiferromagnetic order, which competes with the superconductivity. However, in the nonmagnetic state, there are many aspects of the electronic instabilities that remain unclarified, as represented by the orbital instability and several in-plane anisotropic physical properties. We report a new aspect of the electronic state of the optimally doped iron-based superconductors by using high-energy resolution angle-resolved photoemission spectroscopy. We find spectral evidence for the folded electronic structure suggestive of an antiferroic electronic instability, coexisting with the superconductivity in the nonmagnetic state of Ba1-x K x Fe2As2. We further establish a phase diagram showing that the antiferroic electronic structure persists in a large portion of the nonmagnetic phase covering the superconducting dome. These results motivate consideration of a key unknown electronic instability, which is necessary for the achievement of high-Tc superconductivity in the iron-based superconductors.
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Affiliation(s)
- Takahiro Shimojima
- Quantum-Phase Electronics Center and Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Walid Malaeb
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- Department of Physics, Faculty of Science, Beirut Arab University, Beirut 11-5020, Lebanon
| | - Asuka Nakamura
- Quantum-Phase Electronics Center and Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
| | - Takeshi Kondo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Kunihiro Kihou
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Chul-Ho Lee
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Akira Iyo
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Hiroshi Eisaki
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Shigeyuki Ishida
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Masamichi Nakajima
- Department of Physics, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Shin-ichi Uchida
- Department of Physics, University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Kenya Ohgushi
- Department of Physics, Graduate School of Science, Tohoku University, 6-3, Aramaki Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Kyoko Ishizaka
- Quantum-Phase Electronics Center and Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
| | - Shik Shin
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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43
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Leahy IA, Pocs CA, Siegfried PE, Graf D, Do SH, Choi KY, Normand B, Lee M. Anomalous Thermal Conductivity and Magnetic Torque Response in the Honeycomb Magnet α-RuCl_{3}. PHYSICAL REVIEW LETTERS 2017; 118:187203. [PMID: 28524686 DOI: 10.1103/physrevlett.118.187203] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Indexed: 06/07/2023]
Abstract
We report on the unusual behavior of the in-plane thermal conductivity κ and torque τ response in the Kitaev-Heisenberg material α-RuCl_{3}. κ shows a striking enhancement with linear growth beyond H=7 T, where magnetic order disappears, while τ for both of the in-plane symmetry directions shows an anomaly at the same field. The temperature and field dependence of κ are far more complex than conventional phonon and magnon contributions, and require us to invoke the presence of unconventional spin excitations whose properties are characteristic of a field-induced spin-liquid phase related to the enigmatic physics of the Kitaev model in an applied magnetic field.
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Affiliation(s)
- Ian A Leahy
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Christopher A Pocs
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Peter E Siegfried
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - David Graf
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - S-H Do
- Department of Physics, Chung-Ang University, Seoul 790-784, South Korea
| | - Kwang-Yong Choi
- Department of Physics, Chung-Ang University, Seoul 790-784, South Korea
| | - B Normand
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Minhyea Lee
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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44
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Harter JW, Zhao ZY, Yan JQ, Mandrus DG, Hsieh D. A parity-breaking electronic nematic phase transition in the spin-orbit coupled metal Cd
2
Re
2
O
7. Science 2017; 356:295-299. [DOI: 10.1126/science.aad1188] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 03/20/2017] [Indexed: 11/02/2022]
Affiliation(s)
- J. W. Harter
- Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA 91125, USA
| | - Z. Y. Zhao
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA
| | - J.-Q. Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - D. G. Mandrus
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - D. Hsieh
- Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA 91125, USA
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45
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Fernandes RM, Chubukov AV. Low-energy microscopic models for iron-based superconductors: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:014503. [PMID: 27876709 DOI: 10.1088/1361-6633/80/1/014503] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The development of sensible microscopic models is essential to elucidate the normal-state and superconducting properties of the iron-based superconductors. Because these materials are mostly metallic, a good starting point is an effective low-energy model that captures the electronic states near the Fermi level and their interactions. However, in contrast to cuprates, iron-based high-T c compounds are multi-orbital systems with Hubbard and Hund interactions, resulting in a rather involved 10-orbital lattice model. Here we review different minimal models that have been proposed to unveil the universal features of these systems. We first review minimal models defined solely in the orbital basis, which focus on a particular subspace of orbitals, or solely in the band basis, which rely only on the geometry of the Fermi surface. The former, while providing important qualitative insight into the role of the orbital degrees of freedom, do not distinguish between high-energy and low-energy sectors and, for this reason, generally do not go beyond mean-field. The latter allow one to go beyond mean-field and investigate the interplay between superconducting and magnetic orders as well as Ising-nematic order. However, they cannot capture orbital-dependent features like spontaneous orbital order. We then review recent proposals for a minimal model that operates in the band basis but fully incorporates the orbital composition and symmetries of the low-energy excitations. We discuss the results of the renormalization group study of such a model, particularly of the interplay between superconductivity, magnetism, and spontaneous orbital order, and compare theoretical predictions with experiments on iron pnictides and chalcogenides. We also discuss the impact of the glide-plane symmetry on the low-energy models, highlighting the key role played by the spin-orbit coupling.
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46
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Liu M, Sternbach AJ, Basov DN. Nanoscale electrodynamics of strongly correlated quantum materials. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:014501. [PMID: 27811387 DOI: 10.1088/0034-4885/80/1/014501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Electronic, magnetic, and structural phase inhomogeneities are ubiquitous in strongly correlated quantum materials. The characteristic length scales of the phase inhomogeneities can range from atomic to mesoscopic, depending on their microscopic origins as well as various sample dependent factors. Therefore, progress with the understanding of correlated phenomena critically depends on the experimental techniques suitable to provide appropriate spatial resolution. This requirement is difficult to meet for some of the most informative methods in condensed matter physics, including infrared and optical spectroscopy. Yet, recent developments in near-field optics and imaging enabled a detailed characterization of the electromagnetic response with a spatial resolution down to 10 nm. Thus it is now feasible to exploit at the nanoscale well-established capabilities of optical methods for characterization of electronic processes and lattice dynamics in diverse classes of correlated quantum systems. This review offers a concise description of the state-of-the-art near-field techniques applied to prototypical correlated quantum materials. We also discuss complementary microscopic and spectroscopic methods which reveal important mesoscopic dynamics of quantum materials at different energy scales.
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Affiliation(s)
- Mengkun Liu
- Department of Physics, Stony Brook University, Stony Brook, NY 11794, USA
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47
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Wang PS, Sun SS, Cui Y, Song WH, Li TR, Yu R, Lei H, Yu W. Pressure Induced Stripe-Order Antiferromagnetism and First-Order Phase Transition in FeSe. PHYSICAL REVIEW LETTERS 2016; 117:237001. [PMID: 27982652 DOI: 10.1103/physrevlett.117.237001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Indexed: 06/06/2023]
Abstract
To elucidate the magnetic structure and the origin of the nematicity in FeSe, we perform a high-pressure ^{77}Se NMR study on FeSe single crystals. We find a suppression of the structural transition temperature with pressure up to about 2 GPa from the anisotropy of the Knight shift. Above 2 GPa, a stripe-order antiferromagnetism that breaks the spatial fourfold rotational symmetry is determined by the NMR spectra under different field orientations and with temperatures down to 50 mK. The magnetic phase transition is revealed to be first-order type, implying the existence of a concomitant structural transition via a spin-lattice coupling. Stripe-type spin fluctuations are observed at high temperatures, and remain strong with pressure. These results provide clear evidence for strong coupling between nematicity and magnetism in FeSe, and therefore support a universal scenario of magnetic driven nematicity in iron-based superconductors.
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Affiliation(s)
- P S Wang
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - S S Sun
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - Y Cui
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - W H Song
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - T R Li
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - Rong Yu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
- Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China and Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Hechang Lei
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - Weiqiang Yu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
- Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China and Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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Coupled multiple-mode theory for s ± pairing mechanism in iron based superconductors. Sci Rep 2016; 6:37508. [PMID: 27897177 PMCID: PMC5126631 DOI: 10.1038/srep37508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/27/2016] [Indexed: 11/21/2022] Open
Abstract
We investigate the interplay between the magnetic and the superconducting degrees of freedom in unconventional multi-band superconductors such as iron pnictides. For this purpose a dynamical mode-mode coupling theory is developed based on the coupled Bethe-Salpeter equations. In order to investigate the region of the phase diagram not too far from the tetracritical point where the magnetic spin density wave, (SDW) and superconducting (SC) transition temperatures coincide, we also construct a Ginzburg-Landau functional including both SC and SDW fluctuations in a critical region above the transition temperatures. The fluctuation corrections tend to suppress the magnetic transition, but in the superconducting channel the intraband and interband contribution of the fluctuations nearly compensate each other.
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Zhang W, Park JT, Lu X, Wei Y, Ma X, Hao L, Dai P, Meng ZY, Yang YF, Luo H, Li S. Effect of Nematic Order on the Low-Energy Spin Fluctuations in Detwinned BaFe_{1.935}Ni_{0.065}As_{2}. PHYSICAL REVIEW LETTERS 2016; 117:227003. [PMID: 27925732 DOI: 10.1103/physrevlett.117.227003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Indexed: 06/06/2023]
Abstract
The origin of nematic order remains one of the major debates in iron-based superconductors. In theories based on spin nematicity, one major prediction is that the spin-spin correlation length at (0,π) should decrease with decreasing temperature below the structural transition temperature T_{s}. Here, we report inelastic neutron scattering studies on the low-energy spin fluctuations in BaFe_{1.935}Ni_{0.065}As_{2} under uniaxial pressure. Both intensity and spin-spin correlation start to show anisotropic behavior at high temperature, while the reduction of the spin-spin correlation length at (0,π) happens just below T_{s}, suggesting the strong effect of nematic order on low-energy spin fluctuations. Our results favor the idea that treats the spin degree of freedom as the driving force of the electronic nematic order.
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Affiliation(s)
- Wenliang Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J T Park
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, D-85748 Garching, Germany
| | - Xingye Lu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yuan Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaoyan Ma
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Lijie Hao
- China Institute of Atomic Energy, Beijing 102413, China
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005-1827, USA
| | - Zi Yang Meng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yi-Feng Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Shiliang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
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Xiao H, Gao B, Ma YH, Li XJ, Mu G, Hu T. Superconducting fluctuation effect in CaFe0.88Co0.12AsF. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:455701. [PMID: 27619794 DOI: 10.1088/0953-8984/28/45/455701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Out-of-plane angular dependent torque measurements were performed on CaFe0.88Co0.12AsF single crystals. Superconducting fluctuations, featured by magnetic field enhanced and exponential temperature dependent diamagnetism, are observed above the superconducting transition temperature T c, which is similar to that of cuprate superconductors, but less pronounced. In addition, the ratio of T c versus superfluid density follows well the Uemura line of high-T c cuprates, which suggests the exotic nature of the superconductivity in CaFe0.88Co0.12AsF.
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Affiliation(s)
- H Xiao
- Center for High Pressure Science and Technology Advanced Research, Beijing, 100094, People's Republic of China
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