1
|
Ogata S, Kitagawa S, Kinjo K, Ishida K, Brando M, Hassinger E, Geibel C, Khim S. Parity Transition of Spin-Singlet Superconductivity Using Sublattice Degrees of Freedom. PHYSICAL REVIEW LETTERS 2023; 130:166001. [PMID: 37154635 DOI: 10.1103/physrevlett.130.166001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 03/24/2023] [Indexed: 05/10/2023]
Abstract
Recently, a superconducting (SC) transition from low-field (LF) to high-field (HF) SC states was reported in CeRh_{2}As_{2}, indicating the existence of multiple SC states. It has been theoretically noted that the existence of two Ce sites in the unit cell, the so-called sublattice degrees of freedom owing to the local inversion symmetry breaking at the Ce sites, can lead to the appearance of multiple SC phases even under an interaction inducing spin-singlet superconductivity. CeRh_{2}As_{2} is considered as the first example of multiple SC phases owing to this sublattice degree of freedom. However, microscopic information about the SC states has not yet been reported. In this study, we measured the SC spin susceptibility at two crystallographically inequivalent As sites using nuclear magnetic resonance for various magnetic fields. Our experimental results strongly indicate a spin-singlet state in both SC phases. In addition, the antiferromagnetic phase, which appears within the SC phase, only coexists with the LF SC phase; there is no sign of magnetic ordering in the HF SC phase. The present Letter reveals unique SC properties originating from the locally noncentrosymmetric characteristics.
Collapse
Affiliation(s)
- Shiki Ogata
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | | | - Katsuki Kinjo
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Kenji Ishida
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Manuel Brando
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Elena Hassinger
- Technical University Dresden, Institute for Solid State and Materials Physics, 01062 Dresden, Germany
| | - Christoph Geibel
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Seunghyun Khim
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| |
Collapse
|
2
|
Emergent anisotropy in the Fulde-Ferrell-Larkin-Ovchinnikov state. Nat Commun 2022; 13:5590. [PMID: 36192393 PMCID: PMC9530125 DOI: 10.1038/s41467-022-33354-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 09/08/2022] [Indexed: 11/08/2022] Open
Abstract
Exotic superconductivity is formed by unconventional electron pairing and exhibits various unique properties that cannot be explained by the basic theory. The Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state is known as an exotic superconducting state in that the electron pairs have a finite center-of-mass momentum leading to a spatially modulated pattern of superconductivity. The spatial modulation endows the FFLO state with emergent anisotropy. However, the anisotropy has never been experimentally verified despite numerous efforts over the years. Here, we report detection of anisotropic acoustic responses depending on the sound propagation direction appearing above the Pauli limit. This anisotropy reveals that the two-dimensional FFLO state has a center-of-mass momentum parallel to the nesting vector on the Fermi surface. The present findings will facilitate our understanding of not only superconductivity in solids but also exotic pairings of various particles. The famous Fulde–Ferrell–Larkin– Ovchinnikov (FFLO) state is a spatially-modulated superconducting state with a predicted spatial anisotropy, but this anisotropy has never been experimentally verified. Here, the authors present ultrasound evidence for anisotropy of the sound velocity in the FFLO state of a 2D organic superconductor.
Collapse
|
3
|
Kinjo K, Manago M, Kitagawa S, Mao ZQ, Yonezawa S, Maeno Y, Ishida K. Superconducting spin smecticity evidencing the Fulde-Ferrell-Larkin-Ovchinnikov state in Sr 2RuO 4. Science 2022; 376:397-400. [PMID: 35446631 DOI: 10.1126/science.abb0332] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Translational symmetry breaking is antagonistic to static fluidity but can be realized in superconductors, which host a quantum-mechanical coherent fluid formed by electron pairs. A peculiar example of such a state is the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, induced by a time-reversal symmetry-breaking magnetic field applied to spin-singlet superconductors. This state is intrinsically accompanied by the superconducting spin smecticity, spin density-modulated fluidity with spontaneous translational-symmetry breaking. Detection of such spin smecticity provides unambiguous evidence for the FFLO state, but its observation has been challenging. Here, we report the characteristic "double-horn" nuclear magnetic resonance spectrum in the layered superconductor Sr2RuO4 near its upper critical field, indicating the spatial sinusoidal modulation of spin density that is consistent with superconducting spin smecticity. Our work reveals that Sr2RuO4 provides a versatile platform for studying FFLO physics.
Collapse
Affiliation(s)
- K Kinjo
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - M Manago
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | | | - Z Q Mao
- Department of Physics, Pennsylvania State University, State College, PA, USA
| | - S Yonezawa
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Y Maeno
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - K Ishida
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto, Japan
| |
Collapse
|
4
|
Abstract
Our work shows a fascinating application of finite-momentum superconductivity, the supercurrent diode effect, which is being reported in a growing number of experiments. We show that, under external magnetic field, Cooper pairs can acquire finite momentum so that critical currents in the direction parallel and antiparallel to the Cooper pair momentum become unequal. When both inversion and time-reversal symmetries are broken, the critical current of a superconductor can be nonreciprocal. In this work, we show that, in certain classes of two-dimensional superconductors with antisymmetric spin–orbit coupling, Cooper pairs acquire a finite momentum upon the application of an in-plane magnetic field, and, as a result, critical currents in the direction parallel and antiparallel to the Cooper pair momentum become unequal. This supercurrent diode effect is also manifested in the polarity dependence of in-plane critical fields induced by a supercurrent. These nonreciprocal effects may be found in polar SrTiO3 film, few-layer MoTe2 in the Td phase, and twisted bilayer graphene in which the valley degree of freedom plays a role analogous to spin.
Collapse
|
5
|
Kibune M, Kitagawa S, Kinjo K, Ogata S, Manago M, Taniguchi T, Ishida K, Brando M, Hassinger E, Rosner H, Geibel C, Khim S. Observation of Antiferromagnetic Order as Odd-Parity Multipoles inside the Superconducting Phase in CeRh_{2}As_{2}. PHYSICAL REVIEW LETTERS 2022; 128:057002. [PMID: 35179930 DOI: 10.1103/physrevlett.128.057002] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 11/03/2021] [Indexed: 06/14/2023]
Abstract
Spatial inversion symmetry in crystal structures is closely related to the superconducting (SC) and magnetic properties of materials. Recently, several theoretical proposals that predict various interesting phenomena caused by the breaking of the local inversion symmetry have been presented. However, experimental validation has not yet progressed owing to the lack of model materials. Here we present evidence for antiferromagnetic (AFM) order in CeRh_{2}As_{2} (SC transition temperature T_{SC}∼0.37 K), wherein the Ce site breaks the local inversion symmetry. The evidence is based on the observation of different extents of broadening of the nuclear quadrupole resonance spectrum at two crystallographically inequivalent As sites. This AFM ordering breaks the inversion symmetry of this system, resulting in the activation of an odd-parity magnetic multipole. Moreover, the onset of antiferromagnetism T_{N} within an SC phase, with T_{N}<T_{SC}, is quite unusual in systems wherein superconductivity coexists or competes with magnetism. Our observations show that CeRh_{2}As_{2} is a promising system to study how the absence of local inversion symmetry induces or influences unconventional magnetic and SC states, as well as their interaction.
Collapse
Affiliation(s)
- Mayu Kibune
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | | | - Katsuki Kinjo
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Shiki Ogata
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Masahiro Manago
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | | | - Kenji Ishida
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Manuel Brando
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Elena Hassinger
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Helge Rosner
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Christoph Geibel
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Seunghyun Khim
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| |
Collapse
|
6
|
Lin SZ, Kim DY, Bauer ED, Ronning F, Thompson JD, Movshovich R. Interplay of the Spin Density Wave and a Possible Fulde-Ferrell-Larkin-Ovchinnikov State in CeCoIn_{5} in Rotating Magnetic Field. PHYSICAL REVIEW LETTERS 2020; 124:217001. [PMID: 32530696 DOI: 10.1103/physrevlett.124.217001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 06/11/2023]
Abstract
The d-wave superconductor CeCoIn_{5} has been proposed as a strong candidate for supporting the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state near the low-temperature boundary of its upper critical field. Neutron diffraction, however, finds spin-density-wave (SDW) order in this part of the phase diagram for field in the a-b plane, and evidence for the SDW disappears as the applied field is rotated toward the tetragonal c axis. It is important to understand the interplay between the SDW and a possible FFLO state in CeCoIn_{5}, as the mere existence of an SDW does not necessarily exclude an FFLO state. Here, based on a model constructed on the basis of available experiments, we show that an FFLO state competes with an SDW phase. The SDW state in CeCoIn_{5} is stabilized when the field is directed close to the a-b plane. When the field is rotated toward the c axis, the FFLO state emerges, and the SDW phase disappears. In the FFLO state, the nodal planes with extra quasiparticles (where the superconducting order parameter is zero) are perpendicular to the field, and in the SDW phase, the quasiparticle density of states is reduced. We test this model prediction by measuring heat transported by normal quasiparticles in the superconducting state. As a function of field, we observe a reduction of thermal conductivity for field close to the a-b plane and an enhancement of thermal conductivity when field is close to the c axis, consistent with theoretical expectations. Our modeling and experiments, therefore, indicate the existence of the FFLO state when field is parallel to the c axis.
Collapse
Affiliation(s)
- Shi-Zeng Lin
- Theoretical Division, T-4 and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Duk Y Kim
- MPA-CMMS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon 16419, Republic of Korea
| | - Eric D Bauer
- MPA-CMMS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Filip Ronning
- MPA-CMMS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J D Thompson
- MPA-CMMS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Roman Movshovich
- MPA-CMMS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| |
Collapse
|
7
|
Kasahara S, Sato Y, Licciardello S, Čulo M, Arsenijević S, Ottenbros T, Tominaga T, Böker J, Eremin I, Shibauchi T, Wosnitza J, Hussey NE, Matsuda Y. Evidence for an Fulde-Ferrell-Larkin-Ovchinnikov State with Segmented Vortices in the BCS-BEC-Crossover Superconductor FeSe. PHYSICAL REVIEW LETTERS 2020; 124:107001. [PMID: 32216412 DOI: 10.1103/physrevlett.124.107001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 02/05/2020] [Indexed: 06/10/2023]
Abstract
We present resistivity and thermal-conductivity measurements of superconducting FeSe in intense magnetic fields up to 35 T applied parallel to the ab plane. At low temperatures, the upper critical field μ_{0}H_{c2}^{ab} shows an anomalous upturn, while thermal conductivity exhibits a discontinuous jump at μ_{0}H^{*}≈24 T well below μ_{0}H_{c2}^{ab}, indicating a first-order phase transition in the superconducting state. This demonstrates the emergence of a distinct field-induced superconducting phase. Moreover, the broad resistive transition at high temperatures abruptly becomes sharp upon entering the high-field phase, indicating a dramatic change of the magnetic-flux properties. We attribute the high-field phase to the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state, where the formation of planar nodes gives rise to a segmentation of the flux-line lattice. We point out that strongly orbital-dependent pairing as well as spin-orbit interactions, the multiband nature, and the extremely small Fermi energy are important for the formation of the FFLO state in FeSe.
Collapse
Affiliation(s)
- S Kasahara
- Department of Physics, Kyoto University, Kyoto 606-8502 Japan
| | - Y Sato
- Department of Physics, Kyoto University, Kyoto 606-8502 Japan
| | - S Licciardello
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
| | - M Čulo
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
| | - S Arsenijević
- Hochfeld-Magnetlabor Dresden (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, D-01328 Dresden, Germany
| | - T Ottenbros
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
| | - T Tominaga
- Department of Physics, Kyoto University, Kyoto 606-8502 Japan
| | - J Böker
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44801 Bochum, Germany
| | - I Eremin
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44801 Bochum, Germany
- National University of Science and Technology MISiS, 119049 Moscow, Russian Federation
| | - T Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - J Wosnitza
- Hochfeld-Magnetlabor Dresden (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, D-01328 Dresden, Germany
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
| | - N E Hussey
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
- H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, BS8 1TL, United Kingdom
| | - Y Matsuda
- Department of Physics, Kyoto University, Kyoto 606-8502 Japan
| |
Collapse
|
8
|
Levitin LV, Yager B, Sumner L, Cowan B, Casey AJ, Saunders J, Zhelev N, Bennett RG, Parpia JM. Evidence for a Spatially Modulated Superfluid Phase of ^{3}He under Confinement. PHYSICAL REVIEW LETTERS 2019; 122:085301. [PMID: 30932601 DOI: 10.1103/physrevlett.122.085301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 12/12/2018] [Indexed: 06/09/2023]
Abstract
In superfluid ^{3}He-B confined in a slab geometry, domain walls between regions of different order parameter orientation are predicted to be energetically stable. Formation of the spatially modulated superfluid stripe phase has been proposed. We confined ^{3}He in a 1.1 μm high microfluidic cavity and cooled it into the B phase at low pressure, where the stripe phase is predicted. We measured the surface-induced order parameter distortion with NMR, sensitive to the formation of domains. The results rule out the stripe phase, but are consistent with 2D modulated superfluid order.
Collapse
Affiliation(s)
- Lev V Levitin
- Department of Physics, Royal Holloway University of London, Egham, Surrey TW20 0EX, United Kingdom
| | - Ben Yager
- Department of Physics, Royal Holloway University of London, Egham, Surrey TW20 0EX, United Kingdom
| | - Laura Sumner
- Department of Physics, Royal Holloway University of London, Egham, Surrey TW20 0EX, United Kingdom
| | - Brian Cowan
- Department of Physics, Royal Holloway University of London, Egham, Surrey TW20 0EX, United Kingdom
| | - Andrew J Casey
- Department of Physics, Royal Holloway University of London, Egham, Surrey TW20 0EX, United Kingdom
| | - John Saunders
- Department of Physics, Royal Holloway University of London, Egham, Surrey TW20 0EX, United Kingdom
| | - Nikolay Zhelev
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - Robert G Bennett
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - Jeevak M Parpia
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| |
Collapse
|