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Shang T, Svanidze E, Shiroka T. Probing the superconducting pairing of the La 4Be 33Pt 16alloy via muon-spin spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 36:105601. [PMID: 37988753 DOI: 10.1088/1361-648x/ad0e93] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 11/21/2023] [Indexed: 11/23/2023]
Abstract
We report a study of the superconducting pairing of the noncentrosymmetric La4Be33Pt16alloy using muon-spin rotation and relaxation (µSR) technique. BelowTc=2.4 K, La4Be33Pt16exhibits bulk superconductivity (SC), here characterized by heat-capacity and magnetic-susceptibility measurements. The temperature dependence of the superfluid densityρsc(T), extracted from the transverse-fieldµSR measurements, reveals a nodeless SC in La4Be33Pt16. The best fit ofρsc(T)using ans-wave model yields a magnetic penetration depthλ0=542 nm and a superconducting gapΔ0=0.37 meV at zero Kelvin. The single-gapped superconducting state is further evidenced by the temperature-dependent electronic specific heatCe(T)/Tand the linear field-dependent electronic specific-heat coefficientγH(H). The zero-fieldµSR spectra collected in the normal- and superconducting states of La4Be33Pt16are almost identical, confirming the absence of an additional field-related relaxation and, thus, of spontaneous magnetic fields belowTc. The nodeless SC combined with a preserved time-reversal symmetry in the superconducting state proves that the spin-singlet pairing is dominant in La4Be33Pt16. This material represents yet another example of a complex system showing only a conventional behavior, in spite of a noncentrosymmetric structure and a sizeable spin-orbit coupling.
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Affiliation(s)
- Tian Shang
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
- Chongqing Key Laboratory of Precision Optics, Chongqing Institute of East China Normal University, Chongqing 401120, People's Republic of China
| | - Eteri Svanidze
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Toni Shiroka
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH-Hönggerberg, CH-8093 Zürich, Switzerland
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2
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Makhdoumi Kakhaki Z, Leo A, Chianese F, Parlato L, Pepe GP, Nigro A, Cirillo C, Attanasio C. Upper critical magnetic field in NbRe and NbReN micrometric strips. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2023; 14:45-51. [PMID: 36703906 PMCID: PMC9830497 DOI: 10.3762/bjnano.14.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 12/19/2022] [Indexed: 06/18/2023]
Abstract
Non-centrosymmetric superconductors have recently received significant interest due to their intriguing physical properties such as multigap and nodal superconductivity, helical vortex states, as well as non-trivial topological effects. Moreover, large values of the upper critical magnetic field have been reported in these materials. Here, we focus on the study of the temperature dependence of the perpendicular magnetic field of NbRe and NbReN films patterned in micrometric strips. The experimental data are studied within the Werthamer-Helfand-Hohenberg theory, which considers both orbital and Zeeman pair breaking. The analysis of the results shows different behavior for the two materials with a Pauli contribution relevant only in the case of NbReN.
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Affiliation(s)
- Zahra Makhdoumi Kakhaki
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, I-84084 Fisciano (Sa), Italy
| | - Antonio Leo
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, I-84084 Fisciano (Sa), Italy
- CNR-SPIN, c/o Università degli Studi di Salerno, I-84084 Fisciano (Sa), Italy
| | - Federico Chianese
- Dipartimento di Fisica “E. Pancini”, Università degli Studi di Napoli Federico II, I-80125 Napoli, Italy
| | - Loredana Parlato
- Dipartimento di Fisica “E. Pancini”, Università degli Studi di Napoli Federico II, I-80125 Napoli, Italy
| | - Giovanni Piero Pepe
- Dipartimento di Fisica “E. Pancini”, Università degli Studi di Napoli Federico II, I-80125 Napoli, Italy
| | - Angela Nigro
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, I-84084 Fisciano (Sa), Italy
- CNR-SPIN, c/o Università degli Studi di Salerno, I-84084 Fisciano (Sa), Italy
| | - Carla Cirillo
- CNR-SPIN, c/o Università degli Studi di Salerno, I-84084 Fisciano (Sa), Italy
| | - Carmine Attanasio
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, I-84084 Fisciano (Sa), Italy
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3
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Shang T, Zhao J, Hu LH, Ma J, Gawryluk DJ, Zhu X, Zhang H, Zhen Z, Yu B, Xu Y, Zhan Q, Pomjakushina E, Shi M, Shiroka T. Unconventional superconductivity in topological Kramers nodal-line semimetals. SCIENCE ADVANCES 2022; 8:eabq6589. [PMID: 36306356 PMCID: PMC9616505 DOI: 10.1126/sciadv.abq6589] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 09/09/2022] [Indexed: 06/16/2023]
Abstract
Crystalline symmetry is a defining factor of the electronic band topology in solids, where many-body interactions often induce a spontaneous breaking of symmetry. Superconductors lacking an inversion center are among the best systems to study such effects or even to achieve topological superconductivity. Here, we demonstrate that TRuSi materials (with T a transition metal) belong to this class. Their bulk normal states behave as three-dimensional Kramers nodal-line semimetals, characterized by large antisymmetric spin-orbit couplings and by hourglass-like dispersions. Our muon-spin spectroscopy measurements show that certain TRuSi compounds spontaneously break the time-reversal symmetry at the superconducting transition, while unexpectedly showing a fully gapped superconductivity. Their unconventional behavior is consistent with a unitary (s + ip) pairing, reflecting a mixture of spin singlets and spin triplets. By combining an intrinsic time-reversal symmetry-breaking superconductivity with nontrivial electronic bands, TRuSi compounds provide an ideal platform for investigating the rich interplay between unconventional superconductivity and the exotic properties of Kramers nodal-line/hourglass fermions.
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Affiliation(s)
- Tian Shang
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Jianzhou Zhao
- Co-Innovation Center for New Energetic Materials, Southwest University of Science and Technology, Mianyang 621010, China
| | - Lun-Hui Hu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA
| | - Junzhang Ma
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong
| | - Dariusz Jakub Gawryluk
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Xiaoyan Zhu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Hui Zhang
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Zhixuan Zhen
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Bocheng Yu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Yang Xu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Qingfan Zhan
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Ekaterina Pomjakushina
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Ming Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Toni Shiroka
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich, Switzerland
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4
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Tay D, Shang T, Qi YP, Ying TP, Hosono H, Ott HR, Shiroka T. s-wave superconductivity in the noncentrosymmetric W 3Al 2C superconductor: an NMR study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:194005. [PMID: 35193132 DOI: 10.1088/1361-648x/ac577a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/22/2022] [Indexed: 06/14/2023]
Abstract
We report on a microscopic study of the noncentrosymmetric superconductor W3Al2C (withTc= 7.6 K), mostly by means of27Al- and13C nuclear magnetic resonance (NMR). Since in this material the density of states at the Fermi level is dominated by the tungsten's 5dorbitals, we expect a sizeable spin-orbit coupling (SOC) effect. The normal-state electronic properties of W3Al2C resemble those of a standard metal, but with a Korringa product 1/(T1T) significantly smaller than that of metallic Al, reflecting the marginal role played bys-electrons. In the superconducting state, we observe a reduction of the Knight shift and an exponential decrease of the NMR relaxation rate 1/T1, typical ofs-wave superconductivity (SC). This is further supported by the observation of a small but distinct coherence peak just belowTcin the13C NMR relaxation-rate, in agreement with the fully-gapped superconducting state inferred from the electronic specific-heat data well belowTc. The above features are compared to those of members of the same family, in particular, Mo3Al2C, often claimed to exhibit unconventional SC. We discuss why, despite the enhanced SOC, W3Al2C does not show spin-triplet features in its superconducting state and consider the broader consequences of our results for noncentrosymmetric superconductors in general.
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Affiliation(s)
- D Tay
- Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zurich, Switzerland
| | - T Shang
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
| | - Y P Qi
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - T P Ying
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - H Hosono
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - H-R Ott
- Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zurich, Switzerland
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - T Shiroka
- Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zurich, Switzerland
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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5
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Huddart BM, Onuorah IJ, Isah MM, Bonfà P, Blundell SJ, Clark SJ, De Renzi R, Lancaster T. Intrinsic Nature of Spontaneous Magnetic Fields in Superconductors with Time-Reversal Symmetry Breaking. PHYSICAL REVIEW LETTERS 2021; 127:237002. [PMID: 34936766 DOI: 10.1103/physrevlett.127.237002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 08/27/2021] [Accepted: 10/27/2021] [Indexed: 06/14/2023]
Abstract
We present a systematic investigation of muon-stopping states in superconductors that reportedly exhibit spontaneous magnetic fields below their transition temperatures due to time-reversal symmetry breaking. These materials include elemental rhenium, several intermetallic systems, and Sr_{2}RuO_{4}. We demonstrate that the presence of the muon leads to only a limited and relatively localized perturbation to the local crystal structure, while any small changes to the electronic structure occur several electron volts below the Fermi energy, leading to only minimal changes in the charge density on ions close to the muon. Our results imply that the muon-induced perturbation alone is unlikely to lead to the observed spontaneous fields in these materials, whose origin is more likely intrinsic to the time-reversal symmetry-broken superconducting state.
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Affiliation(s)
- B M Huddart
- Department of Physics, Centre for Materials Physics, Durham University, Durham DH1 3LE, United Kingdom
| | - I J Onuorah
- Department of Mathematical, Physical and Computer Sciences, University of Parma, 43124 Parma, Italy
| | - M M Isah
- Department of Mathematical, Physical and Computer Sciences, University of Parma, 43124 Parma, Italy
| | - P Bonfà
- Department of Mathematical, Physical and Computer Sciences, University of Parma, 43124 Parma, Italy
| | - S J Blundell
- Department of Physics, Clarendon Laboratory, Oxford University, Parks Road, Oxford OX1 3PU, United Kingdom
| | - S J Clark
- Department of Physics, Centre for Materials Physics, Durham University, Durham DH1 3LE, United Kingdom
| | - R De Renzi
- Department of Mathematical, Physical and Computer Sciences, University of Parma, 43124 Parma, Italy
| | - T Lancaster
- Department of Physics, Centre for Materials Physics, Durham University, Durham DH1 3LE, United Kingdom
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Meinero M, Bonfà P, Onuorah IJ, Sanna S, De Renzi R, Eremin I, Müller MA, Orain JC, Martinelli A, Provino A, Manfrinetti P, Putti M, Shiroka T, Lamura G. Mn-induced Fermi-surface reconstruction in the SmFeAsO parent compound. Sci Rep 2021; 11:14373. [PMID: 34257347 PMCID: PMC8277866 DOI: 10.1038/s41598-021-93625-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 06/22/2021] [Indexed: 11/17/2022] Open
Abstract
The electronic ground state of iron-based materials is unusually sensitive to electronic correlations. Among others, its delicate balance is profoundly affected by the insertion of magnetic impurities in the FeAs layers. Here, we address the effects of Fe-to-Mn substitution in the non-superconducting Sm-1111 pnictide parent compound via a comparative study of SmFe[Formula: see text]Mn[Formula: see text]AsO samples with [Formula: see text] 0.05 and 0.10. Magnetization, Hall effect, and muon-spin spectroscopy data provide a coherent picture, indicating a weakening of the commensurate Fe spin-density-wave (SDW) order, as shown by the lowering of the SDW transition temperature [Formula: see text] with increasing Mn content, and the unexpected appearance of another magnetic order, occurring at [Formula: see text] and 20 K for [Formula: see text] and 0.10, respectively. We attribute the new magnetic transition at [Formula: see text], occurring well inside the SDW phase, to a reorganization of the Fermi surface due to Fe-to-Mn substitutions. These give rise to enhanced magnetic fluctuations along the incommensurate wavevector [Formula: see text], further increased by the RKKY interactions among Mn impurities.
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Affiliation(s)
- M Meinero
- Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, 16146, Genova, Italy
- CNR-SPIN, Corso Perrone 24, 16152, Genova, Italy
| | - P Bonfà
- Dipartimento di Scienze Matematiche, Fisiche ed Informatiche, Università di Parma, Parco delle Scienze, 7a, 43124, Parma, Italy
| | - I J Onuorah
- Dipartimento di Scienze Matematiche, Fisiche ed Informatiche, Università di Parma, Parco delle Scienze, 7a, 43124, Parma, Italy
| | - S Sanna
- Dipartimento di Fisica e Astronomia "A. Righi", Università di Bologna, Viale Berti Pichat 6/2, 40127, Bologna, Italy
| | - R De Renzi
- Dipartimento di Scienze Matematiche, Fisiche ed Informatiche, Università di Parma, Parco delle Scienze, 7a, 43124, Parma, Italy
| | - I Eremin
- Theoretische Physik III, Ruhr-Universität Bochum, 44801, Bochum, Germany
- National University of Science and Technology MISiS, 119049, Moscow, Russian Federation
| | - M A Müller
- Theoretische Physik III, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - J-C Orain
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - A Martinelli
- CNR-SPIN, Corso Perrone 24, 16152, Genova, Italy
| | - A Provino
- CNR-SPIN, Corso Perrone 24, 16152, Genova, Italy
- Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ, 08854-8019, USA
| | - P Manfrinetti
- CNR-SPIN, Corso Perrone 24, 16152, Genova, Italy
- Dipartimento di Chimica e Chimica Industriale, Università di Genova, via Dodecaneso 31, 16146, Genova, Italy
| | - M Putti
- Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, 16146, Genova, Italy
- CNR-SPIN, Corso Perrone 24, 16152, Genova, Italy
| | - T Shiroka
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH-Hönggerberg, 8093, Zürich, Switzerland
| | - G Lamura
- CNR-SPIN, Corso Perrone 24, 16152, Genova, Italy.
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7
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Grinenko V, Das D, Gupta R, Zinkl B, Kikugawa N, Maeno Y, Hicks CW, Klauss HH, Sigrist M, Khasanov R. Unsplit superconducting and time reversal symmetry breaking transitions in Sr 2RuO 4 under hydrostatic pressure and disorder. Nat Commun 2021; 12:3920. [PMID: 34168141 PMCID: PMC8225887 DOI: 10.1038/s41467-021-24176-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 06/01/2021] [Indexed: 11/23/2022] Open
Abstract
There is considerable evidence that the superconducting state of Sr2RuO4 breaks time reversal symmetry. In the experiments showing time reversal symmetry breaking, its onset temperature, TTRSB, is generally found to match the critical temperature, Tc, within resolution. In combination with evidence for even parity, this result has led to consideration of a dxz ± idyz order parameter. The degeneracy of the two components of this order parameter is protected by symmetry, yielding TTRSB = Tc, but it has a hard-to-explain horizontal line node at kz = 0. Therefore, s ± id and d ± ig order parameters are also under consideration. These avoid the horizontal line node, but require tuning to obtain TTRSB ≈ Tc. To obtain evidence distinguishing these two possible scenarios (of symmetry-protected versus accidental degeneracy), we employ zero-field muon spin rotation/relaxation to study pure Sr2RuO4 under hydrostatic pressure, and Sr1.98La0.02RuO4 at zero pressure. Both hydrostatic pressure and La substitution alter Tc without lifting the tetragonal lattice symmetry, so if the degeneracy is symmetry-protected, TTRSB should track changes in Tc, while if it is accidental, these transition temperatures should generally separate. We observe TTRSB to track Tc, supporting the hypothesis of dxz ± idyz order.
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Affiliation(s)
- Vadim Grinenko
- Institute for Solid State and Materials Physics, Technische Universität Dresden, Dresden, Germany.
- Leibniz-Institut für Festkörper- und Werkstoffforschung (IFW) Dresden, Dresden, Germany.
| | - Debarchan Das
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Villigen, Switzerland
| | - Ritu Gupta
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Villigen, Switzerland
| | - Bastian Zinkl
- Institute for Theoretical Physics, ETH Zurich, Zurich, Switzerland
| | - Naoki Kikugawa
- National Institute for Materials Science, Tsukuba, Japan
| | | | - Clifford W Hicks
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
- School of Physics and Astronomy, University of Birmingham, Birmingham, UK
| | - Hans-Henning Klauss
- Institute for Solid State and Materials Physics, Technische Universität Dresden, Dresden, Germany
| | - Manfred Sigrist
- Institute for Theoretical Physics, ETH Zurich, Zurich, Switzerland.
| | - Rustem Khasanov
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Villigen, Switzerland.
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8
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Ghosh SK, Smidman M, Shang T, Annett JF, Hillier AD, Quintanilla J, Yuan H. Recent progress on superconductors with time-reversal symmetry breaking. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 33:033001. [PMID: 32721940 DOI: 10.1088/1361-648x/abaa06] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 07/28/2020] [Indexed: 06/11/2023]
Abstract
Superconductivity and magnetism are adversarial states of matter. The presence of spontaneous magnetic fields inside the superconducting state is, therefore, an intriguing phenomenon prompting extensive experimental and theoretical research. In this review, we discuss recent experimental discoveries of unconventional superconductors which spontaneously break time-reversal symmetry and theoretical efforts in understanding their properties. We discuss the main experimental probes and give an extensive account of theoretical approaches to understand the order parameter symmetries and the corresponding pairing mechanisms, including the importance of multiple bands.
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Affiliation(s)
- Sudeep Kumar Ghosh
- Physics of Quantum Materials, School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - Michael Smidman
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Tian Shang
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, Villigen CH-5232, Switzerland
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - James F Annett
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Adrian D Hillier
- ISIS Facility, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, United Kingdom
| | - Jorge Quintanilla
- Physics of Quantum Materials, School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - Huiqiu Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
- State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
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9
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Shang T, Smidman M, Wang A, Chang LJ, Baines C, Lee MK, Nie ZY, Pang GM, Xie W, Jiang WB, Shi M, Medarde M, Shiroka T, Yuan HQ. Simultaneous Nodal Superconductivity and Time-Reversal Symmetry Breaking in the Noncentrosymmetric Superconductor CaPtAs. PHYSICAL REVIEW LETTERS 2020; 124:207001. [PMID: 32501078 DOI: 10.1103/physrevlett.124.207001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/12/2020] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
By employing a series of experimental techniques, we provide clear evidence that CaPtAs represents a rare example of a noncentrosymmetric superconductor which simultaneously exhibits nodes in the superconducting gap and broken time-reversal symmetry (TRS) in its superconducting state (below T_{c}≈1.5 K). Unlike in fully gapped superconductors, the magnetic penetration depth λ(T) does not saturate at low temperatures, but instead it shows a T^{2} dependence, characteristic of gap nodes. Both the superfluid density and the electronic specific heat are best described by a two-gap model comprising of a nodeless gap and a gap with nodes, rather than by single-band models. At the same time, zero-field muon-spin relaxation spectra exhibit increased relaxation rates below the onset of superconductivity, implying that TRS is broken in the superconducting state of CaPtAs, hence indicating its unconventional nature. Our observations suggest CaPtAs to be a new remarkable material that links two apparently disparate classes, that of TRS-breaking correlated magnetic superconductors with nodal gaps and the weakly correlated noncentrosymmetric superconductors with broken TRS, normally exhibiting only a fully gapped behavior.
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Affiliation(s)
- T Shang
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, Villigen CH-5232, Switzerland
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, Zürich CH-8057, Switzerland
| | - M Smidman
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - A Wang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - L-J Chang
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - C Baines
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, Villigen PSI CH-5232, Switzerland
| | - M K Lee
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - Z Y Nie
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - G M Pang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - W Xie
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - W B Jiang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - M Medarde
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - T Shiroka
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, Villigen PSI CH-5232, Switzerland
- Laboratorium für Festkörperphysik, ETH Zürich, Zürich CH-8093, Switzerland
| | - H Q Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing Univeristy, Nanjing 210093, China
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10
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Singh D, Sajilesh KP, Marik S, Biswas PK, Hillier AD, Singh RP. Nodeless s-wave superconductivity in the [Formula: see text]-Mn structure type noncentrosymmetric superconductor TaOs: a [Formula: see text]SR study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:015602. [PMID: 31509816 DOI: 10.1088/1361-648x/ab43a4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Noncentrosymmetric superconductors can lead to a variety of exotic properties in the superconducting state such as line nodes, multigap behavior, and time-reversal symmetry breaking. In this paper, we report the properties of a new noncentrosymmetric superconductor TaOs, using muon spin relaxation and rotation measurements. It is shown using the zero-field muon experiment that TaOs preserve the time-reversal symmetry in the superconducting state. From the transverse field muon measurements, we extract the temperature dependence of [Formula: see text], which is proportional to the superfluid density. This data can be fit with a fully gapped s-wave model for [Formula: see text] = 2.01 [Formula: see text] 0.02. Furthermore, the value of magnetic penetration depth is found to be 5919 [Formula: see text] 45 [Formula: see text], which is consistent with the value obtained from the bulk measurements.
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Affiliation(s)
- D Singh
- Indian Institute of Science Education and Research Bhopal, Bhopal, 462066, India
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