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Zhang JL, Chen W, Liu HT, Li Y, Wang Z, Huang W. Quantum-Geometry-Induced Anomalous Hall Effect in Nonunitary Superconductors and Application to Sr_{2}RuO_{4}. PHYSICAL REVIEW LETTERS 2024; 132:136001. [PMID: 38613301 DOI: 10.1103/physrevlett.132.136001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 03/01/2024] [Indexed: 04/14/2024]
Abstract
The polar Kerr effect and the closely related anomalous charge Hall effect are among the most distinguishing signatures of the superconducting state in Sr_{2}RuO_{4}, as well as in several other compounds. These effects are often thought to be derived from chiral superconducting pairing, and different mechanisms have been invoked for the explanation. However, the intrinsic mechanisms proposed previously often involve unrealistically strong interband Cooper pairing. We show in this Letter that, even without interband pairing, nonunitary superconducting states can support the intrinsic anomalous charge Hall effect, thanks to the quantum geometric properties of the Bloch electrons. The key here is to have a normal-state spin Hall effect, for which a nonzero spin-orbit coupling is essential. A finite charge Hall effect then naturally arises at the onset of a spin-polarized nonunitary superconducting pairing. It depends on both the spin polarization and the normal-state electron Berry curvature, the latter of which is the imaginary part of the quantum geometric tensor of the Bloch states. Applying our results to the weakly paired Sr_{2}RuO_{4} we conclude that, if the reported Kerr effect is of intrinsic origin, the superconducting state is most likely nonunitary and has odd parity. Our theory may be generalized to other superconductors that exhibit the polar Kerr effect.
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Affiliation(s)
- Jia-Long Zhang
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong SAR, China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Weipeng Chen
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
- International Quantum Academy, Shenzhen 518048, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Hao-Tian Liu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
- International Quantum Academy, Shenzhen 518048, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yu Li
- Institute of Quantum Materials and Physics, Henan Academy of Sciences, Zhengzhou, Henan 450046, China
- Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Zhiqiang Wang
- Department of Physics and James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - Wen Huang
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
- International Quantum Academy, Shenzhen 518048, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
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2
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Gassner S, Weber CS, Claassen M. Light-induced switching between singlet and triplet superconducting states. Nat Commun 2024; 15:1776. [PMID: 38413590 PMCID: PMC10899631 DOI: 10.1038/s41467-024-45949-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 02/08/2024] [Indexed: 02/29/2024] Open
Abstract
While the search for topological triplet-pairing superconductivity has remained a challenge, recent developments in optically stabilizing metastable superconducting states suggest a new route to realizing this elusive phase. Here, we devise a testable theory of competing superconducting orders that permits ultrafast switching to an opposite-parity superconducting phase in centrosymmetric crystals with strong spin-orbit coupling. Using both microscopic and phenomenological models, we show that dynamical inversion symmetry breaking with a tailored light pulse can induce odd-parity (spin triplet) order parameter oscillations in a conventional even-parity (spin singlet) superconductor, which when driven strongly can send the system to a competing minimum in its free energy landscape. Our results provide new guiding principles for engineering unconventional electronic phases using light, suggesting a fundamentally non-equilibrium route toward realizing topological superconductivity.
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Affiliation(s)
- Steven Gassner
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Clara S Weber
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Institut für Theorie der Statistischen Physik, RWTH Aachen and JARA - Fundamentals of Future Information Technology, D-52056, Aachen, Germany
| | - Martin Claassen
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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3
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Khasanov R, Ramires A, Grinenko V, Shipulin I, Kikugawa N, Sokolov DA, Krieger JA, Hicken TJ, Maeno Y, Luetkens H, Guguchia Z. In-Plane Magnetic Penetration Depth in Sr_{2}RuO_{4}: Muon-Spin Rotation and Relaxation Study. PHYSICAL REVIEW LETTERS 2023; 131:236001. [PMID: 38134793 DOI: 10.1103/physrevlett.131.236001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 12/24/2023]
Abstract
We report on measurements of the in-plane magnetic penetration depth (λ_{ab}) in single crystals of Sr_{2}RuO_{4} down to ≃0.015 K by means of muon-spin rotation-relaxation. The linear temperature dependence of λ_{ab}^{-2} for T≲0.7 K suggests the presence of nodes in the superconducting gap. This statement is further substantiated by observation of the Volovik effect, i.e., the reduction of λ_{ab}^{-2} as a function of the applied magnetic field. The experimental zero-field and zero-temperature value of λ_{ab}=124(3) nm agrees with λ_{ab}≃130 nm, calculated based on results of electronic structure measurements reported in A. Tamai et al. [High-resolution photoemission on Sr_{2}RuO_{4} reveals correlation-enhanced effective spin-orbit coupling and dominantly local self-energies, Phys. Rev. X 9, 021048 (2019)PRXHAE2160-330810.1103/PhysRevX.9.021048]. Our analysis reveals that a simple nodal superconducting energy gap, described by the lowest possible harmonic of a gap function, does not capture the dependence of λ_{ab}^{-2} on T, so the higher angular harmonics of the energy gap function need to be introduced.
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Affiliation(s)
- Rustem Khasanov
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Aline Ramires
- Laboratory for Theoretical and Computational Physics, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Vadim Grinenko
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 201210, China
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ilya Shipulin
- Leibniz Institute for Solid State and Materials Research, 01069 Dresden, Germany
| | - Naoki Kikugawa
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0003, Japan
| | - Dmitry A Sokolov
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Jonas A Krieger
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Thomas J Hicken
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Yoshiteru Maeno
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
- Toyota Riken - Kyoto University Research Center (TRiKUC), Kyoto 606-8501, Japan
| | - Hubertus Luetkens
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Zurab Guguchia
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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4
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Yazdani-Hamid M. Effect of nonequilibrium order parameter on the optical response of superconductor Sr 2RuO 4. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:455603. [PMID: 36041424 DOI: 10.1088/1361-648x/ac8dd2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 08/30/2022] [Indexed: 06/15/2023]
Abstract
The breaking of time reversal symmetry of the superconducting pairings is expected to manifest itself through characteristic transport properties such as a non-zero Kerr angle which provides fingerprint of the quantum anomalous Hall state. In this work, we theoretically study the Kerr effect or the Hall-type response and also consider how this response is modified by the nonequilibrium shape of order parameter of the superconducting state due to the influence of the electromagnetic radiation for the most favorable candidates of chiral superconducting order parameters and of the non-chiral states in strontium ruthenate (Sr2RuO4). The unique sensitivity of the Hall-type response introduced above to different types of pairings can be used to identify the most favored pairing which is a serious doubt on the superconducting state of this material.
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Affiliation(s)
- Meghdad Yazdani-Hamid
- Department of Physics, Ayatollah Boroujerdi University, Boroujerd, Lorestan 65151-36111, Iran
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5
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Jerzembeck F, Røising HS, Steppke A, Rosner H, Sokolov DA, Kikugawa N, Scaffidi T, Simon SH, Mackenzie AP, Hicks CW. The superconductivity of Sr 2RuO 4 under c-axis uniaxial stress. Nat Commun 2022; 13:4596. [PMID: 35933412 PMCID: PMC9357014 DOI: 10.1038/s41467-022-32177-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 07/19/2022] [Indexed: 11/15/2022] Open
Abstract
Applying in-plane uniaxial pressure to strongly correlated low-dimensional systems has been shown to tune the electronic structure dramatically. For example, the unconventional superconductor Sr2RuO4 can be tuned through a single Van Hove point, resulting in strong enhancement of both Tc and Hc2. Out-of-plane (c axis) uniaxial pressure is expected to tune the quasi-two-dimensional structure even more strongly, by pushing it towards two Van Hove points simultaneously. Here, we achieve a record uniaxial stress of 3.2 GPa along the c axis of Sr2RuO4. Hc2 increases, as expected for increasing density of states, but unexpectedly Tc falls. As a first attempt to explain this result, we present three-dimensional calculations in the weak interaction limit. We find that within the weak-coupling framework there is no single order parameter that can account for the contrasting effects of in-plane versus c-axis uniaxial stress, which makes this new result a strong constraint on theories of the superconductivity of Sr2RuO4. In the superconductor Sr2RuO4, in-plane strain is known to enhance both the superconducting transition temperature Tc and upper critical field Hc2, but the effect of out-of-plane strain has not been studied. Here, the authors find that Hc2 is enhanced under out-of-plane strain, but Tc unexpectedly decreases.
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Affiliation(s)
- Fabian Jerzembeck
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str 40, 01187, Dresden, Germany.
| | - Henrik S Røising
- Nordita, KTH Royal Institute of Technology and Stockholm University, Hannes Alfvéns väg 12, SE-106 91, Stockholm, Sweden
| | - Alexander Steppke
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str 40, 01187, Dresden, Germany
| | - Helge Rosner
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str 40, 01187, Dresden, Germany
| | - Dmitry A Sokolov
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str 40, 01187, Dresden, Germany
| | - Naoki Kikugawa
- National Institute for Materials Science, Tsukuba, 305-0003, Japan
| | - Thomas Scaffidi
- Department of Physics, University of Toronto, Toronto, ON, M5S 1A7, Canada.,Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Steven H Simon
- Rudolf Peierls Center for Theoretical Physics, Oxford, OX1 3PU, UK
| | - Andrew P Mackenzie
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str 40, 01187, Dresden, Germany. .,Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK.
| | - Clifford W Hicks
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str 40, 01187, Dresden, Germany. .,School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK.
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6
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Marques CA, Rhodes LC, Fittipaldi R, Granata V, Yim CM, Buzio R, Gerbi A, Vecchione A, Rost AW, Wahl P. Magnetic-Field Tunable Intertwined Checkerboard Charge Order and Nematicity in the Surface Layer of Sr 2 RuO 4. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2100593. [PMID: 34176160 DOI: 10.1002/adma.202100593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/21/2021] [Indexed: 06/13/2023]
Abstract
In strongly correlated electron materials, the electronic, spin, and charge degrees of freedom are closely intertwined. This often leads to the stabilization of emergent orders that are highly sensitive to external physical stimuli promising opportunities for technological applications. In perovskite ruthenates, this sensitivity manifests in dramatic changes of the physical properties with subtle structural details of the RuO6 octahedra, stabilizing enigmatic correlated ground states, from a hotly debated superconducting state via electronic nematicity and metamagnetic quantum criticality to ferromagnetism. Here, it is demonstrated that the rotation of the RuO6 octahedra in the surface layer of Sr2 RuO4 generates new emergent orders not observed in the bulk material. Through atomic-scale spectroscopic characterization of the low-energy electronic states, four van Hove singularities are identified in the vicinity of the Fermi energy. The singularities can be directly linked to intertwined nematic and checkerboard charge order. Tuning of one of these van Hove singularities by magnetic field is demonstrated, suggesting that the surface layer undergoes a Lifshitz transition at a magnetic field of ≈32T. The results establish the surface layer of Sr2 RuO4 as an exciting 2D correlated electron system and highlight the opportunities for engineering the low-energy electronic states in these systems.
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Affiliation(s)
- Carolina A Marques
- School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - Luke C Rhodes
- School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - Rosalba Fittipaldi
- CNR-SPIN, UOS Salerno, Via Giovanni Paolo II 132, Fisciano, I-84084, Italy
| | - Veronica Granata
- Dipartimento di Fisica "E. R. Caianiello" Universitá di Salerno, Fisciano, Salerno, I-84084, Italy
| | - Chi Ming Yim
- School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - Renato Buzio
- CNR-SPIN, Corso F.M. Perrone 24, Genova, 16152, Italy
| | - Andrea Gerbi
- CNR-SPIN, Corso F.M. Perrone 24, Genova, 16152, Italy
| | - Antonio Vecchione
- CNR-SPIN, UOS Salerno, Via Giovanni Paolo II 132, Fisciano, I-84084, Italy
| | - Andreas W Rost
- School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
- Max-Planck-Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Peter Wahl
- School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
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7
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Chronister A, Pustogow A, Kikugawa N, Sokolov DA, Jerzembeck F, Hicks CW, Mackenzie AP, Bauer ED, Brown SE. Evidence for even parity unconventional superconductivity in Sr 2RuO 4. Proc Natl Acad Sci U S A 2021; 118:e2025313118. [PMID: 34161272 PMCID: PMC8237678 DOI: 10.1073/pnas.2025313118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Unambiguous identification of the superconducting order parameter symmetry in [Formula: see text] has remained elusive for more than a quarter century. While a chiral p-wave ground state analogue to superfluid 3He-A was ruled out only very recently, other proposed triplet-pairing scenarios are still viable. Establishing the condensate magnetic susceptibility reveals a sharp distinction between even-parity (singlet) and odd-parity (triplet) pairing since the superconducting condensate is magnetically polarizable only in the latter case. Here field-dependent 17O Knight shift measurements, being sensitive to the spin polarization, are compared to previously reported specific heat measurements for the purpose of distinguishing the condensate contribution from that due to quasiparticles. We conclude that the shift results can be accounted for entirely by the expected field-induced quasiparticle response. An upper bound for the condensate magnetic response of <10% of the normal state susceptibility is sufficient to exclude all purely odd-parity candidates.
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Affiliation(s)
- Aaron Chronister
- Department of Physics & Astronomy, University of California, Los Angeles, CA 90095;
| | - Andrej Pustogow
- Department of Physics & Astronomy, University of California, Los Angeles, CA 90095;
| | - Naoki Kikugawa
- Cryogenic Center for Liquid Hydrogen and Materials Science, National Institute for Materials Science, Tsukuba 305-0003, Japan
| | - Dmitry A Sokolov
- Physics of Quantum Materials Department, Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany
| | - Fabian Jerzembeck
- Physics of Quantum Materials Department, Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany
| | - Clifford W Hicks
- Physics of Quantum Materials Department, Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany
- School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Andrew P Mackenzie
- Physics of Quantum Materials Department, Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Eric D Bauer
- Materials Physics and Applications, Los Alamos National Laboratory, Los Alamos, NM 87545
| | - Stuart E Brown
- Department of Physics & Astronomy, University of California, Los Angeles, CA 90095;
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8
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Kim J, Mun J, Palomares García CM, Kim B, Perry RS, Jo Y, Im H, Lee HG, Ko EK, Chang SH, Chung SB, Kim M, Robinson JWA, Yonezawa S, Maeno Y, Wang L, Noh TW. Superconducting Sr 2RuO 4 Thin Films without Out-of-Phase Boundaries by Higher-Order Ruddlesden-Popper Intergrowth. NANO LETTERS 2021; 21:4185-4192. [PMID: 33979525 DOI: 10.1021/acs.nanolett.0c04963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Ruddlesden-Popper (RP) phases (An+1BnO3n+1, n = 1, 2,···) have attracted intensive research with diverse functionalities for device applications. However, the realization of a high-quality RP-phase film is hindered by the formation of out-of-phase boundaries (OPBs) that occur at terrace edges, originating from lattice mismatch in the c-axis direction with the A'B'O3 (n = ∞) substrate. Here, using strontium ruthenate RP-phase Sr2RuO4 (n = 1) as a model system, an experimental approach for suppressing OPBs was developed. By tuning the growth parameters, the Sr3Ru2O7 (n = 2) phase was formed in a controlled manner near the film-substrate interface. This higher-order RP-phase then blocked the subsequent formation of OPBs, resulting in nearly defect-free Sr2RuO4 layer at the upper region of the film. Consequently, the Sr2RuO4 thin films exhibited superconductivity up to 1.15 K, which is the highest among Sr2RuO4 films grown by pulsed laser deposition. This work paves the way for synthesizing pristine RP-phase heterostructures and exploring their unique physical properties.
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Affiliation(s)
- Jinkwon Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Junsik Mun
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Carla M Palomares García
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Bongju Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Robin S Perry
- London Centre for Nanotechnology and UCL Centre for Materials Discovery, University College London, London WC1E 6BT, United Kingdom
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Yongcheol Jo
- Quantum Functional Semiconductor Research Center (QSRC), Dongguk University, Seoul 04620, Republic of Korea
| | - Hyunsik Im
- Division of Physics and Semiconductor Science, Dongguk University, Seoul 04620, Republic of Korea
| | - Han Gyeol Lee
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Eun Kyo Ko
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Seo Hyoung Chang
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Suk Bum Chung
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
- Natural Science Research Institute, University of Seoul, Seoul 02504, Republic of Korea
- School of Physics, Korea Institute for Advanced Study, Seoul 02455, Republic of Korea
| | - Miyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Jason W A Robinson
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Shingo Yonezawa
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Yoshiteru Maeno
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Lingfei Wang
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
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9
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Electronic Structure Correspondence of Singlet-Triplet Scale Separation in Strained Sr2RuO4. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11020508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
At a temperature of roughly 1 K, Sr2RuO4 undergoes a transition from a normal Fermi liquid to a superconducting phase. Even while the former is relatively simple and well understood, the superconducting state has not even been understood after 25 years of study. More recently, it has been found that critical temperatures can be enhanced by the application of uniaxial strain, up to a critical strain, after which it falls off. In this work, we take an “instability” approach and seek divergences in susceptibilities. This provides an unbiased way to distinguish tendencies to competing ground states. We show that in the unstrained compound, the singlet and triplet instabilities of the normal Fermi liquid phase are closely spaced. Under uniaxial strain, electrons residing on all orbitals contributing to the Fermiology become more coherent, while the electrons of the Ru-dxy character become heavier, and the electrons of the Ru-dxz,yz characters become lighter. In the process, Im χ(q,ω) increases rapidly around q = (0.3,0.3,0)2π/a and q = (0.5,0.25,0)2π/a, while it gets suppressed at all other commensurate vectors, in particular at q = 0, which is essential for spin-triplet superconductivity. We observe that the magnetic anisotropy under strain drops smoothly, which is concomitant with the increment in singlet instability. Thus, the triplet superconducting instability remains the lagging instability of the system, and the singlet instability enhances under strain, leading to a large energy-scale separation between these competing instabilities. However, since this happens even without spin-orbit coupling, we believe it is primarily the enhancement in the spin fluctuation glue around quasi-anti-ferromagnetic vectors that drives the Cooper pairing instead of the magnetic anisotropy. At large strain, an instability to a spin density wave overtakes the superconducting one. The analysis relies on a high-fidelity, ab initio description of the one-particle properties and two-particle susceptibilities, based on the quasiparticle self-consistent GW approximation augmented by dynamical mean field theory. This approach is described and its high fidelity confirmed by comparing to observed one- and two-particle properties.
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10
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Petsch AN, Zhu M, Enderle M, Mao ZQ, Maeno Y, Mazin II, Hayden SM. Reduction of the Spin Susceptibility in the Superconducting State of Sr_{2}RuO_{4} Observed by Polarized Neutron Scattering. PHYSICAL REVIEW LETTERS 2020; 125:217004. [PMID: 33275021 DOI: 10.1103/physrevlett.125.217004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 07/01/2020] [Accepted: 10/14/2020] [Indexed: 06/12/2023]
Abstract
Recent observations [A. Pustogow et al., Nature (London) 574, 72 (2019).NATUAS0028-083610.1038/s41586-019-1596-2] of a drop of the ^{17}O nuclear magnetic resonance (NMR) Knight shift in the superconducting state of Sr_{2}RuO_{4} challenged the popular picture of a chiral odd-parity paired state in this compound. Here we use polarized neutron scattering (PNS) to show that there is a 34±6% drop in the magnetic susceptibility at the Ru site below the superconducting transition temperature. We measure at lower fields H∼1/3H_{c2} than a previous PNS study allowing the suppression to be observed. The PNS measurements show a smaller susceptibility suppression than NMR measurements performed at similar field and temperature. Our results rule out the chiral odd-parity d=z[over ^](k_{x}±ik_{y}) state and are consistent with several recent proposals for the order parameter including even-parity B_{1g} and odd-parity helical states.
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Affiliation(s)
- A N Petsch
- H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - M Zhu
- H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
| | | | - Z Q Mao
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Y Maeno
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - I I Mazin
- Department of Physics and Astronomy, George Mason University and Quantum Science and Engineering Center, Fairfax, Virginia 22030, USA
| | - S M Hayden
- H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
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11
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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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