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Ishihara J, Mori T, Suzuki T, Sato S, Morita K, Kohda M, Ohno Y, Miyajima K. Imprinting Spatial Helicity Structure of Vector Vortex Beam on Spin Texture in Semiconductors. PHYSICAL REVIEW LETTERS 2023; 130:126701. [PMID: 37027869 DOI: 10.1103/physrevlett.130.126701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 01/17/2023] [Accepted: 02/13/2023] [Indexed: 06/19/2023]
Abstract
We present the transfer of the spatially variant polarization of topologically structured light to the spatial spin texture in a semiconductor quantum well. The electron spin texture, which is a circular pattern with repeating spin-up and spin-down states whose repetition rate is determined by the topological charge, is directly excited by a vector vortex beam with a spatial helicity structure. The generated spin texture efficiently evolves into a helical spin wave pattern owing to the spin-orbit effective magnetic fields in the persistent spin helix state by controlling the spatial wave number of the excited spin mode. By tuning the repetition length and azimuthal angle, we simultaneously generate helical spin waves with opposite phases by a single beam.
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Affiliation(s)
- Jun Ishihara
- Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan
| | - Takachika Mori
- Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan
| | - Takuya Suzuki
- Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan
| | - Sota Sato
- Graduate School of Electrical and Electronic Engineering, Chiba University, Chiba 263-8522, Japan
| | - Ken Morita
- Graduate School of Electrical and Electronic Engineering, Chiba University, Chiba 263-8522, Japan
| | - Makoto Kohda
- Department of Materials Science, Tohoku University, Sendai 980-8579, Japan
| | - Yuzo Ohno
- Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Kensuke Miyajima
- Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan
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Liu X, Jain JK, Liu CX. Long-Range Spin-Triplet Helix in Proximity Induced Superconductivity in Spin-Orbit-Coupled Systems. PHYSICAL REVIEW LETTERS 2014; 113:227002. [PMID: 25494082 DOI: 10.1103/physrevlett.113.227002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Indexed: 06/04/2023]
Abstract
We study proximity induced triplet superconductivity in a spin-orbit-coupled system, and show that the d vector of the induced triplet superconductivity undergoes precession that can be controlled by varying the relative strengths of Rashba and Dresselhaus spin-orbit couplings. In particular, a long-range spin-triplet helix is predicted when these two spin-orbit couplings have equal strengths. We also study the Josephson junction geometry and show that a transition between 0 and π junctions can be induced by controlling the spin-orbit coupling with a gate voltage. An experimental setup is proposed to verify these effects. Conversely, the observation of these effects can serve as a direct confirmation of triplet superconductivity.
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Affiliation(s)
- Xin Liu
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - J K Jain
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Chao-Xing Liu
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
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Liu X, Sinova J. Reading charge transport from the spin dynamics on the surface of a topological insulator. PHYSICAL REVIEW LETTERS 2013; 111:166801. [PMID: 24182290 DOI: 10.1103/physrevlett.111.166801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Indexed: 06/02/2023]
Abstract
Resolving the conductance of the topological surface states (TSSs) from the bulk contribution has been a great challenge for studying the transport properties of topological insulators. By developing a nonperturbative diffusion equation that describes fully the spin-charge dynamics in the strong spin-orbit coupling regime, we present a proposal to read the charge transport information of TSSs from its spin dynamics which can be isolated from the bulk contribution by the time-resolved second harmonic generation pump-probe measurement. We demonstrate the qualitatively different Dyaknov-Perel spin relaxation behavior between the TSSs and the two-dimensional spin-orbit coupling electron gas. The decay time of both in-plane and out-of-plane spin polarization is naturally proved to be identical to the charge transport time. The out-of-plane spin dynamics is shown to be in the experimentally reachable regime of the femtosecond pump-probe spectroscopy and thereby we suggest experiments to detect the charge transport properties of the TSSs from their unique spin dynamics.
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Affiliation(s)
- Xin Liu
- Department of Physics, Texas A&M University, College Station, Texas 77843-4242, USA and Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
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Shen K, Vignale G. Collective spin Hall effect for electron-hole gratings. PHYSICAL REVIEW LETTERS 2013; 111:136602. [PMID: 24116799 DOI: 10.1103/physrevlett.111.136602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Indexed: 06/02/2023]
Abstract
We show that an electric field parallel to the wave fronts of an electron-hole grating in a GaAs quantum well generates, via the electronic spin Hall effect, a spin grating of the same wave vector and with an amplitude that can exceed 1% of the amplitude of the initial density grating. We refer to this phenomenon as the "collective spin Hall effect." A detailed study of the coupled spin-charge dynamics for quantum wells grown in different directions reveals rich features in the time evolution of the induced spin density, including the possibility of generating a helical spin grating.
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Affiliation(s)
- Ka Shen
- Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA
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Yang L, Koralek JD, Orenstein J, Tibbetts DR, Reno JL, Lilly MP. Coherent propagation of spin helices in a quantum-well confined electron gas. PHYSICAL REVIEW LETTERS 2012; 109:246603. [PMID: 23368357 DOI: 10.1103/physrevlett.109.246603] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Indexed: 06/01/2023]
Abstract
We use phase-resolved transient grating spectroscopy to measure the propagation of spin helices in a high mobility n-GaAs/AlGaAs quantum well with an applied in-plane electric field. At relatively low fields helical modes crossover from overdamped excitations where the spin-precession period exceeds the spin lifetime, to a regime of coherent propagation where several spin-precession periods can be observed. We demonstrate that the envelope of a spin polarization packet reaches a current-driven velocity of 10(7) cm s(-1) in an applied field of 70 V cm(-1).
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Affiliation(s)
- Luyi Yang
- Department of Physics, University of California, Berkeley, California 94720, USA
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Wunderlich J, Park BG, Irvine AC, Zarbo LP, Rozkotova E, Nemec P, Novak V, Sinova J, Jungwirth T. Spin Hall Effect Transistor. Science 2010; 330:1801-4. [DOI: 10.1126/science.1195816] [Citation(s) in RCA: 257] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Burkov AA, Hawthorn DG. Spin and charge transport on the surface of a topological insulator. PHYSICAL REVIEW LETTERS 2010; 105:066802. [PMID: 20867997 DOI: 10.1103/physrevlett.105.066802] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Indexed: 05/29/2023]
Abstract
We derive diffusion equations, which describe spin-charge coupled transport on the helical metal surface of a three-dimensional topological insulator. The main feature of these equations is a large magnitude of the spin-charge coupling, which leads to interesting and observable effects. In particular, we predict a new magnetoresistance effect, which manifests in a non-Ohmic correction to a voltage drop between a ferromagnetic spin-polarized electrode and a nonmagnetic electrode, placed on top of the helical metal. This correction is proportional to the cross product of the spin polarization of the ferromagnetic electrode and the charge current between the two electrodes. We also demonstrate tunability of this effect by applying a gate voltage, which makes it possible to operate the proposed device as a transistor.
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Affiliation(s)
- A A Burkov
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Raghu S, Chung SB, Qi XL, Zhang SC. Collective modes of a helical liquid. PHYSICAL REVIEW LETTERS 2010; 104:116401. [PMID: 20366490 DOI: 10.1103/physrevlett.104.116401] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Indexed: 05/29/2023]
Abstract
We study low energy collective modes and transport properties of the "helical metal" on the surface of a topological insulator. At low energies, electrical transport and spin dynamics at the surface are exactly related by an operator identity equating the electric current to the in-plane components of the spin degrees of freedom. From this relation it follows that an undamped spin wave always accompanies the sound mode in the helical metal-thus it is possible to "hear" the sound of spins. In the presence of long range Coulomb interactions, the surface plasmon mode is also coupled to the spin wave, giving rise to a hybridized "spin-plasmon" mode. We make quantitative predictions for the spin-plasmon in Bi2Se3, and discuss its detection in a spin-grating experiment.
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Affiliation(s)
- S Raghu
- Department of Physics, McCullough Building, Stanford University, Stanford, California 94305-4045, USA
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Hankiewicz EM, Vignale G. Spin-Hall effect and spin-Coulomb drag in doped semiconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:253202. [PMID: 21828424 DOI: 10.1088/0953-8984/21/25/253202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this review, we describe in detail two important spin-transport phenomena: the extrinsic spin-Hall effect (coming from spin-orbit interactions between electrons and impurities) and the spin-Coulomb drag. The interplay of these two phenomena is analyzed. In particular, we discuss the influence of scattering between electrons with opposite spins on the spin current and the spin accumulation produced by the spin-Hall effect. Future challenges and open questions are briefly discussed.
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Affiliation(s)
- E M Hankiewicz
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, D-97074 Würzburg, Germany
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Koralek JD, Weber CP, Orenstein J, Bernevig BA, Zhang SC, Mack S, Awschalom DD. Emergence of the persistent spin helix in semiconductor quantum wells. Nature 2009; 458:610-3. [PMID: 19340077 DOI: 10.1038/nature07871] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 01/30/2009] [Indexed: 11/09/2022]
Abstract
According to Noether's theorem, for every symmetry in nature there is a corresponding conservation law. For example, invariance with respect to spatial translation corresponds to conservation of momentum. In another well-known example, invariance with respect to rotation of the electron's spin, or SU(2) symmetry, leads to conservation of spin polarization. For electrons in a solid, this symmetry is ordinarily broken by spin-orbit coupling, allowing spin angular momentum to flow to orbital angular momentum. However, it has recently been predicted that SU(2) can be achieved in a two-dimensional electron gas, despite the presence of spin-orbit coupling. The corresponding conserved quantities include the amplitude and phase of a helical spin density wave termed the 'persistent spin helix'. SU(2) is realized, in principle, when the strengths of two dominant spin-orbit interactions, the Rashba (strength parameterized by alpha) and linear Dresselhaus (beta(1)) interactions, are equal. This symmetry is predicted to be robust against all forms of spin-independent scattering, including electron-electron interactions, but is broken by the cubic Dresselhaus term (beta(3)) and spin-dependent scattering. When these terms are negligible, the distance over which spin information can propagate is predicted to diverge as alpha approaches beta(1). Here we report experimental observation of the emergence of the persistent spin helix in GaAs quantum wells by independently tuning alpha and beta(1). Using transient spin-grating spectroscopy, we find a spin-lifetime enhancement of two orders of magnitude near the symmetry point. Excellent quantitative agreement with theory across a wide range of sample parameters allows us to obtain an absolute measure of all relevant spin-orbit terms, identifying beta(3) as the main SU(2)-violating term in our samples. The tunable suppression of spin relaxation demonstrated in this work is well suited for application to spintronics.
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Affiliation(s)
- J D Koralek
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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Frolov SM, Venkatesan A, Yu W, Folk JA, Wegscheider W. Electrical generation of pure spin currents in a two-dimensional electron gas. PHYSICAL REVIEW LETTERS 2009; 102:116802. [PMID: 19392226 DOI: 10.1103/physrevlett.102.116802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Indexed: 05/27/2023]
Abstract
Pure spin currents are generated and detected in micron-wide channels of a GaAs two-dimensional electron gas, using quantum point contacts in an in-plane magnetic field as injectors and detectors. The enhanced sensitivity to spin transport offered by a nonlocal measurement geometry enables accurate spin current measurements in this widely studied physical system. The polarization of the contacts is used to extract the quantum point contact g factor and provides a test for spontaneous polarization at 0.7 structure. The spin relaxation length in the channel is 30-50 microm over the magnetic field range 3-10 T, much longer than has been reported in GaAs two-dimensional electron gases but shorter than that expected from Dyakonov-Perel relaxation.
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Affiliation(s)
- S M Frolov
- Department of Physics, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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Gangadharaiah S, Sun J, Starykh OA. Spin-orbit-mediated anisotropic spin interaction in interacting electron systems. PHYSICAL REVIEW LETTERS 2008; 100:156402. [PMID: 18518133 DOI: 10.1103/physrevlett.100.156402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Indexed: 05/26/2023]
Abstract
We investigate interactions between spins of strongly correlated electrons subject to the spin-orbit interaction. Our main finding is that of a novel, spin-orbit mediated anisotropic spin-spin coupling of the van der Waals type. Unlike the standard exchange, this interaction does not require the wave functions to overlap. We argue that this ferromagnetic interaction is important in the Wigner crystal state where the exchange processes are severely suppressed. We also comment on the anisotropy of the exchange between spins mediated by the spin-orbital coupling.
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