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Shook AJ, Varga E, Boettcher I, Davis JP. Surface State Dissipation in Confined ^{3}He-A. PHYSICAL REVIEW LETTERS 2024; 132:156001. [PMID: 38682961 DOI: 10.1103/physrevlett.132.156001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 03/15/2024] [Indexed: 05/01/2024]
Abstract
We have studied the power dependence of superfluid Helmholtz resonators in flat (750 and 1800 nm) rectangular channels. In the A phase of superfluid ^{3}He, we observe a nonlinear response for velocities larger than a critical value. The small size of the channels stabilizes a static uniform texture that eliminates dissipative processes produced by changes in the texture. For such a static texture, the lowest velocity dissipative process is due to the pumping of surface bound states into the bulk liquid. We show that the temperature dependence of the critical velocity observed in our devices is consistent with this surface-state dissipation. Characterization of the force-velocity curves of our devices may provide a platform for studying the physics of exotic surface bound states in superfluid ^{3}He.
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Affiliation(s)
- Alexander J Shook
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Emil Varga
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Igor Boettcher
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - John P Davis
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
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Zhang KX, Ju H, Kim H, Cui J, Keum J, Park JG, Lee JS. Broken Inversion Symmetry in Van Der Waals Topological Ferromagnetic Metal Iron Germanium Telluride. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2312824. [PMID: 38161222 DOI: 10.1002/adma.202312824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Indexed: 01/03/2024]
Abstract
Inversion symmetry breaking is critical for many quantum effects and fundamental for spin-orbit torque, which is crucial for next-generation spintronics. Recently, a novel type of gigantic intrinsic spin-orbit torque is established in the topological van der Waals (vdW) magnet iron germanium telluride. However, it remains a puzzle because no clear evidence exists for interlayer inversion symmetry breaking. Here, the definitive evidence of broken inversion symmetry in iron germanium telluride directly measured by the second harmonic generation (SHG) technique is reported. The data show that the crystal symmetry reduces from centrosymmetric P63/mmc to noncentrosymmetric polar P3m1 space group, giving the threefold SHG pattern with dominant out-of-plane polarization. Additionally, the SHG response evolves from an isotropic pattern to a sharp threefold symmetry upon increasing Fe deficiency, mainly due to the transition from random defects to ordered Fe vacancies. Such SHG response is robust against temperature, ensuring unaltered crystalline symmetries above and below the ferromagnetic transition temperature. These findings add crucial new information to the understanding of this interesting vdW metal, iron germanium telluride: band topology, intrinsic spin-orbit torque, and topological vdW polar metal states.
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Affiliation(s)
- Kai-Xuan Zhang
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
- Center for Quantum Materials, Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
- Institute of Applied Physics, Seoul National University, Seoul, 08826, South Korea
| | - Hwiin Ju
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, South Korea
| | - Hyuncheol Kim
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
- Center for Quantum Materials, Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Jingyuan Cui
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
- Center for Quantum Materials, Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Jihoon Keum
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
- Center for Quantum Materials, Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Je-Geun Park
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
- Center for Quantum Materials, Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
- Institute of Applied Physics, Seoul National University, Seoul, 08826, South Korea
| | - Jong Seok Lee
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, South Korea
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Wu H, Sauls JA. Weyl Fermions and broken symmetry phases of laterally confined 3He films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:495402. [PMID: 37625425 DOI: 10.1088/1361-648x/acf42b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 08/25/2023] [Indexed: 08/27/2023]
Abstract
Broken symmetries in topological condensed matter systems have implications for the spectrum of Fermionic excitations confined on surfaces or topological defects. The Fermionic spectrum of confined (quasi-2D)3He-A consists of branches of chiral edge states. The negative energy states are related to the ground-state angular momentum,Lz=(N/2)ℏ, forN/2Cooper pairs. The power law suppression of the angular momentum,Lz(T)≃(N/2)ℏ[1-23(πT/Δ)2]for0⩽T≪Tc, in the fully gapped 2D chiral A-phase reflects the thermal excitation of the chiral edge Fermions. We discuss the effects of wave function overlap, and hybridization between edge states confined near opposing edge boundaries on the edge currents, ground-state angular momentum and ground-state order parameter of superfluid3He thin films. Under strong lateral confinement, the chiral A phase undergoes a sequence of phase transitions, first to a pair density wave (PDW) phase with broken translational symmetry atDc2∼16ξ0. The PDW phase is described by a periodic array of chiral domains with alternating chirality, separated by domain walls. The period of PDW phase diverges as the confinement lengthD→Dc2. The PDW phase breaks time-reversal symmetry, translation invariance, but is invariant under the combination of time-reversal and translation by a one-half period of the PDW. The mass current distribution of the PDW phase reflects this combined symmetry, and originates from the spectra of edge Fermions and the chiral branches bound to the domain walls. Under sufficiently strong confinement a second-order transition occurs to the non-chiral 'polar phase' atDc1∼9ξ0, in which a single p-wave orbital state of Cooper pairs is aligned along the channel.
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Affiliation(s)
- Hao Wu
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, United States of America
| | - J A Sauls
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, United States of America
- Hearne Institute of Theoretical Physics, Louisiana State University, Baton Rouge, LA 70803, United States of America
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Huang GH, Xu ZF, Wu Z. Intrinsic Anomalous Hall Effect in a Bosonic Chiral Superfluid. PHYSICAL REVIEW LETTERS 2022; 129:185301. [PMID: 36374672 DOI: 10.1103/physrevlett.129.185301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/25/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
The anomalous Hall effect has had a profound influence on the understanding of many electronic topological materials but is much less studied in their bosonic counterparts. We predict that an intrinsic anomalous Hall effect exists in a recently realized bosonic chiral superfluid, a p-orbital Bose-Einstein condensate in a 2D hexagonal boron nitride optical lattice [Wang et al., Nature (London) 596, 227 (2021)NATUAS0028-083610.1038/s41586-021-03702-0]. We evaluate the frequency-dependent Hall conductivity within a multi-orbital Bose-Hubbard model that accurately captures the real experimental system. We find that in the high frequency limit, the Hall conductivity is determined by finite loop current correlations on the s-orbital residing sublattice, the latter a defining feature of the system's chirality. In the opposite limit, the dc Hall conductivity can trace its origin back to the noninteracting band Berry curvature at the condensation momentum, although the contribution from atomic interactions can be significant. We discuss available experimental probes to observe this intrinsic anomalous Hall effect at both zero and finite frequencies.
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Affiliation(s)
- Guan-Hua Huang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Zhi-Fang Xu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, 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
| | - Zhigang Wu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, 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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5
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Jiang QD, Balatsky A. Geometric Induction in Chiral Superfluids. PHYSICAL REVIEW LETTERS 2022; 129:016801. [PMID: 35841579 DOI: 10.1103/physrevlett.129.016801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 06/07/2022] [Indexed: 06/15/2023]
Abstract
We explore the properties of chiral superfluid thin films coating a curved surface. Because of the vector nature of the order parameter, a geometric gauge field emerges and leads to a number of observable effects such as anomalous vortex-geometric interaction and curvature-induced mass and spin supercurrents. We apply our theory to several well-known phases of chiral superfluid ^{3}He and derive experimentally observable signatures. We further discuss the cases of flexible geometries where a soft surface can adapt itself to compensate for the strain from the chiral superfluid. The proposed interplay between geometry and chiral superfluid order provides a fascinating avenue to control and manipulate quantum states with strain.
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Affiliation(s)
- Qing-Dong Jiang
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - A Balatsky
- Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullbacken 23, SE-106 91 Stockholm, Sweden
- UCONN, Department of Physics, Storrs, Connecticut 06269, USA
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Matsushita T, Ando J, Masaki Y, Mizushima T, Fujimoto S, Vekhter I. Spin-Nernst Effect in Time-Reversal-Invariant Topological Superconductors. PHYSICAL REVIEW LETTERS 2022; 128:097001. [PMID: 35302805 DOI: 10.1103/physrevlett.128.097001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/05/2022] [Indexed: 06/14/2023]
Abstract
We investigate the spin-Nernst effect in time-reversal-invariant topological superconductors, and show that it provides smoking-gun evidence for helical Cooper pairs. The spin-Nernst effect stems from asymmetric, in spin space, scattering of quasiparticles at nonmagnetic impurities, and generates a transverse spin current by the temperature gradient. Both the sign and the magnitude of the effect sensitively depend on the scattering phase shift at impurity sites. Therefore the spin-Nernst effect is uniquely suitable for identifying time-reversal-invariant topological superconducting orders.
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Affiliation(s)
- Taiki Matsushita
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Jiei Ando
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yusuke Masaki
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Takeshi Mizushima
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Satoshi Fujimoto
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
- Center for Quantum Information and Quantum Biology, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Ilya Vekhter
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803-4001, USA
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Yan J, Yao J, Shvarts V, Du RR, Lin X. Cryogen-free one hundred microkelvin refrigerator. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:025120. [PMID: 33648063 DOI: 10.1063/5.0036497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 02/04/2021] [Indexed: 06/12/2023]
Abstract
A temperature below 100 µK is achieved in a customized cryogen-free dilution refrigerator with a copper-nuclear demagnetization stage. The lowest temperature of conduction electrons of the demagnetization stage is below 100 µK as measured by using a pulsed platinum nuclear magnetic resonance thermometer, and the temperature can remain below 100 µK for over 10 h. A demagnetization magnetic field of up to 9 T and a research magnetic field of up to 12 T can be controlled independently, provided by a coaxial room-temperature-bore cryogen-free magnet.
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Affiliation(s)
- Jiaojie Yan
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Jianing Yao
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Vladimir Shvarts
- Janis Research Company LLC, Wilmington, Massachusetts 01887, USA
| | - Rui-Rui Du
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Xi Lin
- International Center for Quantum Materials, Peking University, Beijing 100871, China
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8
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Ngampruetikorn V, Sauls JA. Impurity-Induced Anomalous Thermal Hall Effect in Chiral Superconductors. PHYSICAL REVIEW LETTERS 2020; 124:157002. [PMID: 32357039 DOI: 10.1103/physrevlett.124.157002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Abstract
Chiral superconductors exhibit novel transport properties that depend on the topology of the order parameter, topology of the Fermi surface, the spectrum of bulk and edge Fermionic excitations, and the structure of the impurity potential. In the case of electronic heat transport, impurities induce an anomalous (zero-field) thermal Hall conductivity that is easily orders of magnitude larger than the quantized edge contribution. The effect originates from branch-conversion scattering of Bogoliubov quasiparticles by the chiral order parameter, induced by potential scattering. The former transfers angular momentum between the condensate and the excitations that transport heat. The anomalous thermal Hall conductivity is shown to depend to the structure of the electron-impurity potential, as well as the winding number ν of the chiral order parameter Δ(p)=|Δ(p)|e^{iνϕ_{p[over ^]}}. The results provide quantitative formulas for interpreting heat transport experiments seeking to identify broken T and P symmetries, as well as the topology of the order parameter for chiral superconductors.
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Affiliation(s)
- Vudtiwat Ngampruetikorn
- Center for Applied Physics and Superconducting Technologies, Department of Physics, Northwestern University, Evanston, Illinois 60208, USA and Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
| | - J A Sauls
- Center for Applied Physics and Superconducting Technologies, Department of Physics, Northwestern University, Evanston, Illinois 60208, USA and Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
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9
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Shomali Z, Asgari R. Spin transfer torque and exchange coupling in Josephson junctions with ferromagnetic superconductor reservoirs. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:035806. [PMID: 31585455 DOI: 10.1088/1361-648x/ab4b1d] [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
In this paper, the spin transfer torque (STT) and the exchange coupling of the Josephson junctions containing the interesting cases of diffusive/ballistic-triplet/singlet ferromagnetic superconductor (FS) materials are investigated. First, the diffusive FS1/F c /FS2 structures with F c being a junction consisting of ferromagnetic and normal metal parts as well as insulating barriers are investigated. Secondly, the ballistic Josephson junction containing the triplet chiral p/wave FS reservoirs is studied. Using the Nazarov quantum circuit theory for the diffusive structures, it is found that the antiparallel/parallel or vice versa parallel/antiparallel transition of the favorable exchange coupling takes place due to the appearance of the only out-of-plane STT. Furthermore, the analyze of the phase difference interval in which an interlayer length-induced antiparallel/parallel transition can be occurred, is performed. Afterward, the mentioned ballistic structure is dealt with solving the 16 [Formula: see text] 16 Bogoliubov-de-Gennes equation. It is found that although the exchange fields of the FS are laid in the z and y direction, the STT interestingly exists in all three directions of x, y and z. This exciting finding suggests that the favorable equilibrium configuration concerning the least exchange coupling occurs in the relative exchange field direction different from 0 or [Formula: see text].
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Affiliation(s)
- Zahra Shomali
- Department of Physics, Tarbiat Modares University, PO Box 14115-175, Tehran, Iran. School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran
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10
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Moroshkin P, Leiderer P, Kono K, Inui S, Tsubota M. Dynamics of the Vortex-Particle Complexes Bound to the Free Surface of Superfluid Helium. PHYSICAL REVIEW LETTERS 2019; 122:174502. [PMID: 31107083 DOI: 10.1103/physrevlett.122.174502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 02/24/2019] [Indexed: 06/09/2023]
Abstract
We present an experimental and theoretical study of the 2D dynamics of electrically charged nanoparticles trapped under a free surface of superfluid helium in a static vertical electric field. We focus on the dynamics of particles driven by the interaction with quantized vortices terminating at the free surface. We identify two types of particle trajectories and the associated vortex structures: vertical linear vortices pinned at the bottom of the container and half-ring vortices traveling along the free surface of the liquid.
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Affiliation(s)
- P Moroshkin
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, 351-0198 Saitama, Japan
- Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, 904-0495 Okinawa, Japan
| | - P Leiderer
- Department of Physics, University of Konstanz, Universitätstrasse 10, 78464 Konstanz, Germany
| | - K Kono
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, 351-0198 Saitama, Japan
- International College of Semiconductor Technology, National Chiao Tung University, Hsinchu 300, Taiwan
| | - S Inui
- Department of Physics, Osaka City University, 3-3-138 Sugimoto, 558-8585 Osaka, Japan
| | - M Tsubota
- Department of Physics, Osaka City University, 3-3-138 Sugimoto, 558-8585 Osaka, Japan
- Nambu Yoichiro Institute of Theoretical and Experimental Physics, The Advanced Research Institute for Natural Science and Technology, Osaka City University, 3-3-138 Sugimoto, 558-8585 Osaka, Japan
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Mizushima T, Machida K. Multifaceted properties of Andreev bound states: interplay of symmetry and topology. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:20150355. [PMID: 29941630 PMCID: PMC6030149 DOI: 10.1098/rsta.2015.0355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/11/2018] [Indexed: 06/08/2023]
Abstract
Andreev bound states (ABSs) ubiquitously emerge as a consequence of non-trivial topological structures of the order parameter of superfluids and superconductors and significantly contribute to thermodynamics and low-energy quantum transport phenomena. We here share the current status of our knowledge on their multifaceted properties such as Majorana fermions and odd-frequency pairing. A unified concept behind ABSs originates from a soliton state in the one-dimensional Dirac equation with mass domain wall and interplay of ABSs with symmetry and topology enrich their physical characteristics. We make an overview of ABSs with a special focus on superfluid 3He. The quantum liquid confined to restricted geometries serves as a rich repository of noteworthy quantum phenomena, such as the mass acquisition of Majorana fermions driven by spontaneous symmetry breaking, topological quantum criticality, Weyl superfluidity and the anomalous magnetic response. The marriage of the superfluid 3He and nano-fabrication techniques will take one to a new horizon of topological quantum phenomena associated with ABSs.This article is part of the theme issue 'Andreev bound states'.
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Affiliation(s)
- T Mizushima
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - K Machida
- Department of Physics, Ritsumeikan University, Kusatsu 525-8577, Japan
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Kasai J, Okamoto Y, Nishioka K, Takagi T, Sasaki Y. Chiral Domain Structure in Superfluid ^{3}He-A Studied by Magnetic Resonance Imaging. PHYSICAL REVIEW LETTERS 2018; 120:205301. [PMID: 29864362 DOI: 10.1103/physrevlett.120.205301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 12/05/2017] [Indexed: 06/08/2023]
Abstract
The existence of a spatially varying texture in superfluid ^{3}He is a direct manifestation of the complex macroscopic wave function. The real space shape of the texture, namely, a macroscopic wave function, has been studied extensively with the help of theoretical modeling but has never been directly observed experimentally with spatial resolution. We have succeeded in visualizing the texture by a specialized magnetic resonance imaging. With this new technology, we have discovered that the macroscopic chiral domains, of which sizes are as large as 1 mm, and corresponding chiral domain walls exist rather stably in ^{3}He-A film at temperatures far below the transition temperature.
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Affiliation(s)
- J Kasai
- Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-Cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Y Okamoto
- Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-Cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - K Nishioka
- Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-Cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - T Takagi
- Department of Applied Physics, University of Fukui, Bunkyo 3-9-1, Fukui 910-8507, Japan
| | - Y Sasaki
- Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-Cho, Sakyo-ku, Kyoto 606-8502, Japan
- Research Center for Low Temperature and Materials Sciences, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan
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13
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Delplace P, Marston JB, Venaille A. Topological origin of equatorial waves. Science 2017; 358:1075-1077. [DOI: 10.1126/science.aan8819] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 09/26/2017] [Indexed: 11/02/2022]
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14
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Tsutsumi Y. Scattering Theory on Surface Majorana Fermions by an Impurity in ^{3}He-B. PHYSICAL REVIEW LETTERS 2017; 118:145301. [PMID: 28430515 DOI: 10.1103/physrevlett.118.145301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Indexed: 06/07/2023]
Abstract
We have formulated the scattering theory on Majorana fermions emerging in the surface bound state of the superfluid ^{3}He B phase (^{3}He-B) by an impurity. By applying the theory to the electron bubble, which is regarded as the impurity, trapped below a free surface of ^{3}He-B, the observed mobility of the electron bubble [J. Phys. Soc. Jpn. 82, 124607 (2013)JUPSAU0031-901510.7566/JPSJ.82.124607] is quantitatively reproduced. The mobility is suppressed in low temperatures from the expected value in the bulk ^{3}He-B by the contribution from the surface Majorana fermions. By contrast, the mobility does not depend on the trapped depth of the electron bubble in spite of the spatial variation of the wave function of the surface Majorana fermions. Our formulated theory demonstrates the depth-independent mobility by considering intermediate states in the scattering process. Therefore, we conclude that the experiment has succeeded in observing Majorana fermions in the surface bound state.
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Affiliation(s)
- Yasumasa Tsutsumi
- Department of Basic Science, University of Tokyo, Meguro, Tokyo 153-8902, Japan
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15
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Manchon A, Koo HC, Nitta J, Frolov SM, Duine RA. New perspectives for Rashba spin-orbit coupling. NATURE MATERIALS 2015; 14:871-882. [PMID: 26288976 DOI: 10.1038/nmat4360] [Citation(s) in RCA: 420] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 06/22/2015] [Indexed: 06/04/2023]
Abstract
In 1984, Bychkov and Rashba introduced a simple form of spin-orbit coupling to explain the peculiarities of electron spin resonance in two-dimensional semiconductors. Over the past 30 years, Rashba spin-orbit coupling has inspired a vast number of predictions, discoveries and innovative concepts far beyond semiconductors. The past decade has been particularly creative, with the realizations of manipulating spin orientation by moving electrons in space, controlling electron trajectories using spin as a steering wheel, and the discovery of new topological classes of materials. This progress has reinvigorated the interest of physicists and materials scientists in the development of inversion asymmetric structures, ranging from layered graphene-like materials to cold atoms. This Review discusses relevant recent and ongoing realizations of Rashba physics in condensed matter.
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Affiliation(s)
- A Manchon
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division, Thuwal 23955-6900, Saudi Arabia
| | - H C Koo
- Center for Spintronics, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok-dong, Seongbukgu, Seoul 136-791, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701, Korea
| | - J Nitta
- Department of Materials Science, Tohoku University, 980-8579 Sendai, Miyagi, Japan
| | - S M Frolov
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - R A Duine
- Institute for Theoretical Physics and Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
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Tada Y, Nie W, Oshikawa M. Orbital angular momentum and spectral flow in two-dimensional chiral superfluids. PHYSICAL REVIEW LETTERS 2015; 114:195301. [PMID: 26024177 DOI: 10.1103/physrevlett.114.195301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Indexed: 06/04/2023]
Abstract
We study the orbital angular momentum (OAM) L_{z} in two-dimensional chiral (p_{x}+ip_{y})^{ν}-wave superfluids (SFs) of N fermions on a disk at zero temperature, in terms of spectral asymmetry and spectral flow. It is shown that L_{z}=νN/2 for any integer ν, in the Bose-Einstein condensation regime. In contrast, in the BCS limit, while the OAM is L_{z}=N/2 for the p+ip-wave SF, for chiral SFs with ν≥2, the OAM is remarkably suppressed as L_{z}=N×O(Δ_{0}/ϵ_{F})≪N, where Δ_{0} is the gap amplitude and ϵ_{F} is the Fermi energy. We demonstrate that the difference between the p+ip-wave SF and the other chiral SFs in the BCS regimes originates from the nature of edge modes and related depairing effects.
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Affiliation(s)
- Yasuhiro Tada
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
| | - Wenxing Nie
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
| | - Masaki Oshikawa
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
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