1
|
Geier M, Krøjer S, von Oppen F, Marcus CM, Flensberg K, Brouwer PW. Non-Abelian Holonomy of Majorana Zero Modes Coupled to a Chaotic Quantum Dot. PHYSICAL REVIEW LETTERS 2024; 132:036604. [PMID: 38307057 DOI: 10.1103/physrevlett.132.036604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 10/24/2023] [Accepted: 12/16/2023] [Indexed: 02/04/2024]
Abstract
If a quantum dot is coupled to a topological superconductor via tunneling contacts, each contact hosts a Majorana zero mode in the limit of zero transmission. Close to a resonance and at a finite contact transparency, the resonant level in the quantum dot couples the Majorana modes, but a ground-state degeneracy per fermion parity subspace remains if the number of Majorana modes coupled to the dot is five or larger. Upon varying shape-defining gate voltages while remaining close to resonance, a nontrivial evolution within the degenerate ground-state manifold is achieved. We characterize the corresponding non-Abelian holonomy for a quantum dot with chaotic classical dynamics using random matrix theory and discuss measurable signatures of the non-Abelian time evolution.
Collapse
Affiliation(s)
- Max Geier
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Svend Krøjer
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Felix von Oppen
- Dahlem Center for Complex Quantum Systems and Physics Department, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Charles M Marcus
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Karsten Flensberg
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Piet W Brouwer
- Dahlem Center for Complex Quantum Systems and Physics Department, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| |
Collapse
|
2
|
Burmistrov IS, Gefen Y, Shapiro DS, Shnirman A. Mesoscopic Stoner Instability in Open Quantum Dots: Suppression of Coleman-Weinberg Mechanism by Electron Tunneling. PHYSICAL REVIEW LETTERS 2020; 124:196801. [PMID: 32469575 DOI: 10.1103/physrevlett.124.196801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 04/29/2020] [Indexed: 06/11/2023]
Abstract
The mesoscopic Stoner instability is an intriguing manifestation of symmetry breaking in isolated metallic quantum dots, underlined by the competition between single-particle energy and Heisenberg exchange interaction. Here we study this phenomenon in the presence of tunnel coupling to a reservoir. We analyze the spin susceptibility of electrons on the quantum dot for different values of couplings and temperature. Our results indicate the existence of a "quantum phase transition" at a critical value of the tunneling coupling, which is determined by the Stoner-enhanced exchange interaction. This quantum phase transition is a manifestation of the suppression of the Coleman-Weinberg mechanism of symmetry breaking, induced by coupling to the reservoir.
Collapse
Affiliation(s)
- I S Burmistrov
- L. D. Landau Institute for Theoretical Physics, Akademika Semenova Avenue 1-a, 142432 Chernogolovka, Russia
- Laboratory for Condensed Matter Physics, National Research University Higher School of Economics, 101000 Moscow, Russia
| | - Y Gefen
- Department of Condensed Matter Physics, Weizmann Institute of Science, 76100 Rehovot, Israel
- Institut für Quantenmaterialien und Technologien, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - D S Shapiro
- Department of Physics, National Research University Higher School of Economics, 101000 Moscow, Russia
- Dukhov Research Institute of Automatics (VNIIA), Moscow 127055, Russia
- V. A. Kotel'nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Moscow 125009, Russia
| | - A Shnirman
- Institut für Quantenmaterialien und Technologien, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
- Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany
| |
Collapse
|
3
|
Kartashov YV, Konotop VV, Modugno M, Sherman EY. Solitons in Inhomogeneous Gauge Potentials: Integrable and Nonintegrable Dynamics. PHYSICAL REVIEW LETTERS 2019; 122:064101. [PMID: 30822068 DOI: 10.1103/physrevlett.122.064101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Indexed: 06/09/2023]
Abstract
We introduce an exactly integrable nonlinear model describing the dynamics of spinor solitons in space-dependent matrix gauge potentials of rather general types. The model is shown to be gauge equivalent to the integrable system of vector nonlinear Schrödinger equations known as the Manakov model. As an example we consider a self-attractive Bose-Einstein condensate with random spin-orbit coupling (SOC). If Zeeman splitting is also included, the system becomes nonintegrable. We illustrate this by considering the random walk of a soliton in a disordered SOC landscape. While at zero Zeeman splitting the soliton moves without scattering along linear trajectories in the random SOC landscape; at nonzero splitting it exhibits strong scattering by the SOC inhomogeneities. For a large Zeeman splitting, the integrability is restored. In this sense, the Zeeman splitting serves as a parameter controlling the crossover between two different integrable limits.
Collapse
Affiliation(s)
- Y V Kartashov
- Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow 108840, Russia
| | - V V Konotop
- Departamento de Física and Centro de Física Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Edifício C8, Lisboa 1749-016, Portugal
| | - M Modugno
- Department of Theoretical Physics and History of Science, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain
- IKERBASQUE Basque Foundation for Science, Bilbao, Spain
| | - E Ya Sherman
- IKERBASQUE Basque Foundation for Science, Bilbao, Spain
- Department of Physical Chemistry, The University of the Basque Country UPV/EHU, 48080 Bilbao, Spain
| |
Collapse
|
4
|
Milivojević M. Symmetric spin-orbit interaction in triple quantum dot and minimisation of spin-orbit leakage in CNOT gate. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:085302. [PMID: 29328053 DOI: 10.1088/1361-648x/aaa736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We analyse spin-orbit interaction in triple quantum dots and show that a symmetric spin-orbit Hamiltonian does not follow the standard form used in double quantum dots, as a consequence of the presence of the third dot in the setup. Furthermore, CNOT implementation schemes based on the exchange interaction were studied. It was shown that an antisymmetric Dzyaloshinsky-Moriya term is the dominant source of spin-orbit leakage from the computational space. We present a simple scheme for the minimisation of leakage that can be implemented in cases where interacting spins enclose parallelogram or equilateral triangle loops.
Collapse
Affiliation(s)
- Marko Milivojević
- Department of Physics, University of Belgrade, Studentski trg 12-16, 11000 Belgrade, Serbia
| |
Collapse
|
5
|
Milivojević M, Stepanenko D. Effective spin Hamiltonian of a gated triple quantum dot in the presence of spin-orbit interaction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:405302. [PMID: 28703716 DOI: 10.1088/1361-648x/aa7f86] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We derive and study the effective spin Hamiltonian of a gated triple quantum dot that includes the effects of spin-orbit interaction and an external magnetic field. In the analysis of the resulting spin interaction in linear and in general triangular geometry of the dots, we show that the pairwise spin interaction does depend on the position of the third dot. The spin-orbit induced anisotropy, in addition to changing its strength, also changes its symmetry with the motion of the third quantum dot outside the linear arrangement. Our results present a simplified model that may be used in the design of quantum computers based on three-spin qubits.
Collapse
Affiliation(s)
- Marko Milivojević
- Department of Physics, University of Belgrade, Studentski trg 12, 11158 Belgrade, Serbia
| | | |
Collapse
|
6
|
Zhang ZZ, Song XX, Luo G, Deng GW, Mosallanejad V, Taniguchi T, Watanabe K, Li HO, Cao G, Guo GC, Nori F, Guo GP. Electrotunable artificial molecules based on van der Waals heterostructures. SCIENCE ADVANCES 2017; 3:e1701699. [PMID: 29062893 PMCID: PMC5650488 DOI: 10.1126/sciadv.1701699] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 09/25/2017] [Indexed: 06/02/2023]
Abstract
Quantum confinement has made it possible to detect and manipulate single-electron charge and spin states. The recent focus on two-dimensional (2D) materials has attracted significant interests on possible applications to quantum devices, including detecting and manipulating either single-electron charging behavior or spin and valley degrees of freedom. However, the most popular model systems, consisting of tunable double-quantum-dot molecules, are still extremely difficult to realize in these materials. We show that an artificial molecule can be reversibly formed in atomically thin MoS2 sandwiched in hexagonal boron nitride, with each artificial atom controlled separately by electrostatic gating. The extracted values for coupling energies at different regimes indicate a single-electron transport behavior, with the coupling strength between the quantum dots tuned monotonically. Moreover, in the low-density regime, we observe a decrease of the conductance with magnetic field, suggesting the observation of Coulomb blockade weak anti-localization. Our experiments demonstrate for the first time the realization of an artificial quantum-dot molecule in a gated MoS2 van der Waals heterostructure, which could be used to investigate spin-valley physics. The compatibility with large-scale production, gate controllability, electron-hole bipolarity, and new quantum degrees of freedom in the family of 2D materials opens new possibilities for quantum electronics and its applications.
Collapse
Affiliation(s)
- Zhuo-Zhi Zhang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiang-Xiang Song
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Gang Luo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Guang-Wei Deng
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Vahid Mosallanejad
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Takashi Taniguchi
- National Institute for Materials Science, Namiki 1-1, Ibaraki 305-0044, Japan
| | - Kenji Watanabe
- National Institute for Materials Science, Namiki 1-1, Ibaraki 305-0044, Japan
| | - Hai-Ou Li
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Gang Cao
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Guang-Can Guo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Franco Nori
- CEMS, RIKEN, Wako-shi, Saitama 351-0198, Japan
- Department of Physics, University of Michigan, Ann Arbor, MI 48109–1040, USA
| | - Guo-Ping Guo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| |
Collapse
|
7
|
Fujita T, Stano P, Allison G, Morimoto K, Sato Y, Larsson M, Park JH, Ludwig A, Wieck AD, Oiwa A, Tarucha S. Signatures of Hyperfine, Spin-Orbit, and Decoherence Effects in a Pauli Spin Blockade. PHYSICAL REVIEW LETTERS 2016; 117:206802. [PMID: 27886503 DOI: 10.1103/physrevlett.117.206802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Indexed: 06/06/2023]
Abstract
We detect in real time interdot tunneling events in a weakly coupled two-electron double quantum dot in GaAs. At finite magnetic fields, we observe two characteristic tunneling times T_{d} and T_{b}, belonging to, respectively, a direct and a blocked (spin-flip-assisted) tunneling. The latter corresponds to the lifting of a Pauli spin blockade, and the tunneling times ratio η=T_{b}/T_{d} characterizes the blockade efficiency. We find pronounced changes in the behavior of η upon increasing the magnetic field, with η increasing, saturating, and increasing again. We explain this behavior as due to the crossover of the dominant blockade-lifting mechanism from the hyperfine to spin-orbit interactions and due to a change in the contribution of the charge decoherence.
Collapse
Affiliation(s)
- T Fujita
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - P Stano
- Center for Emergent Matter Science (CEMS), RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
- Institute of Physics, Slovak Academy of Sciences, 845 11 Bratislava, Slovakia
| | - G Allison
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Center for Emergent Matter Science (CEMS), RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - K Morimoto
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Y Sato
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - M Larsson
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - J-H Park
- Center for Emergent Matter Science (CEMS), RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - A Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, Gebäude NB, D-44780 Bochum, Germany
| | - A D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, Gebäude NB, D-44780 Bochum, Germany
| | - A Oiwa
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - S Tarucha
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Center for Emergent Matter Science (CEMS), RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| |
Collapse
|
8
|
Bercioux D, Lucignano P. Quantum transport in Rashba spin-orbit materials: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2015; 78:106001. [PMID: 26406280 DOI: 10.1088/0034-4885/78/10/106001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this review article we describe spin-dependent transport in materials with spin-orbit interaction of Rashba type. We mainly focus on semiconductor heterostructures, however we consider topological insulators, graphene and hybrid structures involving superconductors as well. We start from the Rashba Hamiltonian in a two dimensional electron gas and then describe transport properties of two- and quasi-one-dimensional systems. The problem of spin current generation and interference effects in mesoscopic devices is described in detail. We address also the role of Rashba interaction on localisation effects in lattices with nontrivial topology, as well as on the Ahronov-Casher effect in ring structures. A brief section, in the end, describes also some related topics including the spin-Hall effect, the transition from weak localisation to weak anti localisation and the physics of Majorana fermions in hybrid heterostructures involving Rashba materials in the presence of superconductivity.
Collapse
Affiliation(s)
- Dario Bercioux
- Donostia International Physics Center (DIPC), Manuel de Lardizbal 4, E-20018 San Sebastián, Spain. IKERBASQUE, Basque Foundation of Science, 48011 Bilbao, Basque Country, Spain. Dahlem Center for Complex Quantum Systems and Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | | |
Collapse
|
9
|
Choe DH, Chang KJ. Universal Conductance Fluctuation in Two-Dimensional Topological Insulators. Sci Rep 2015; 5:10997. [PMID: 26055574 PMCID: PMC4460725 DOI: 10.1038/srep10997] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 05/12/2015] [Indexed: 11/08/2022] Open
Abstract
Despite considerable interest in two-dimensional (2D) topological insulators (TIs), a fundamental question still remains open how mesoscopic conductance fluctuations in 2D TIs are affected by spin-orbit interaction (SOI). Here, we investigate the effect of SOI on the universal conductance fluctuation (UCF) in disordered 2D TIs. Although 2D TI exhibits UCF like any metallic systems, the amplitude of these fluctuations is distinguished from that of conventional spin-orbit coupled 2D materials. Especially, in 2D systems with mirror symmetry, spin-flip scattering is forbidden even in the presence of strong intrinsic SOI, hence increasing the amplitude of the UCF by a factor of √2 compared with extrinsic SOI that breaks mirror symmetry. We propose an easy way to experimentally observe the existence of such spin-flip scattering in 2D materials. Our findings provide a key to understanding the emergence of a new universal behavior in 2D TIs.
Collapse
Affiliation(s)
- Duk-Hyun Choe
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Rep. of Korea
| | - K. J. Chang
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Rep. of Korea
| |
Collapse
|
10
|
Chesi S, Wang YD, Twamley J. Diabolical points in multi-scatterer optomechanical systems. Sci Rep 2015; 5:7816. [PMID: 25588627 PMCID: PMC4295109 DOI: 10.1038/srep07816] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 12/09/2014] [Indexed: 11/18/2022] Open
Abstract
Diabolical points, which originate from parameter-dependent accidental degeneracies of a system's energy levels, have played a fundamental role in the discovery of the Berry phase as well as in photonics (conical refraction), in chemical dynamics, and more recently in novel materials such as graphene, whose electronic band structure possess Dirac points. Here we discuss diabolical points in an optomechanical system formed by multiple scatterers in an optical cavity with periodic boundary conditions. Such configuration is close to experimental setups using micro-toroidal rings with indentations or near-field scatterers. We find that the optomechanical coupling is no longer an analytic function near the diabolical point and demonstrate the topological phase arising through the mechanical motion. Similar to a Fabry-Perot resonator, the optomechanical coupling can grow with the number of scatterers. We also introduce a minimal quantum model of a diabolical point, which establishes a connection to the motion of an arbitrary-spin particle in a 2D parabolic quantum dot with spin-orbit coupling.
Collapse
Affiliation(s)
- Stefano Chesi
- Beijing Computational Science Research Center, Beijing 100084, China
| | - Ying-Dan Wang
- State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of SciencesP.O. Box 2735, Beijing 100190, China
| | - Jason Twamley
- Centre for Engineered Quantum Systems, Department of Physics and Astronomy, Macquarie University, NSW 2109, Australia
| |
Collapse
|
11
|
Kim KW, Lee HW, Lee KJ, Stiles MD. Chirality from interfacial spin-orbit coupling effects in magnetic bilayers. PHYSICAL REVIEW LETTERS 2013; 111:216601. [PMID: 24313509 DOI: 10.1103/physrevlett.111.216601] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Indexed: 06/02/2023]
Abstract
As nanomagnetic devices scale to smaller sizes, spin-orbit coupling due to the broken structural inversion symmetry at interfaces becomes increasingly important. Here, we study interfacial spin-orbit coupling effects in magnetic bilayers using a simple Rashba model. The spin-orbit coupling introduces chirality into the behavior of the electrons and through them into the energetics of the magnetization. In the derived form of the magnetization dynamics, all of the contributions that are linear in the spin-orbit coupling follow from this chirality, considerably simplifying the analysis. For these systems, an important consequence is a correlation between the Dzyaloshinskii-Moriya interaction and the spin-orbit torque. We use this correlation to analyze recent experiments.
Collapse
Affiliation(s)
- Kyoung-Whan Kim
- Basic Science Research Institute, Pohang University of Science and Technology, Pohang 790-784, Korea and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | | | | | | |
Collapse
|
12
|
Urbina JD, Wimmer M, Bauernfeind D, Espitia D, Adagideli İ, Richter K. Universal spatial correlations in random spinor fields. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:042115. [PMID: 23679381 DOI: 10.1103/physreve.87.042115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 12/12/2012] [Indexed: 06/02/2023]
Abstract
We identify universal spatial fluctuations in systems with nontrivial spin dynamics. To this end we calculate by exact numerical diagonalization a variety of experimentally relevant correlations between spinor amplitudes, spin polarizations, and spin currents, both in the bulk and near the boundary of a confined two-dimensional clean electron gas in the presence of spin-orbit interaction. We support our claim of universality with the excellent agreement between the numerical results and system-independent spatial correlations of a random field defined on both the spatial and spin degrees of freedom. A rigorous identity relating our universal predictions with response functions provides a direct physical interpretation of our results in the framework of linear response theory.
Collapse
Affiliation(s)
- Juan Diego Urbina
- Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany
| | | | | | | | | | | |
Collapse
|
13
|
Droste S, Andergassen S, Splettstoesser J. Josephson current through interacting double quantum dots with spin-orbit coupling. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:415301. [PMID: 23006317 DOI: 10.1088/0953-8984/24/41/415301] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We study the effect of Rashba spin-orbit interaction on the Josephson current through a double quantum dot in the presence of Coulomb repulsion. In particular, we describe the characteristic effects on the magnetic field-induced singlet-triplet transition in the molecular regime. Exploring the whole parameter space, we analyze the effects of the device asymmetry, the orientation of the applied magnetic field with respect to the spin-orbit interaction, and finite temperatures. We find that at finite temperatures the orthogonal component of the spin-orbit interaction exhibits a similar effect to the Coulomb interaction inducing the occurrence of a π-phase at particle-hole symmetry. This provides a new route to the experimental observability of the π-phase in multi-level quantum dots.
Collapse
Affiliation(s)
- Stephanie Droste
- Institut für Theorie der Statistischen Physik, RWTH Aachen University, 52056 Aachen, Germany.
| | | | | |
Collapse
|
14
|
Adagideli İ, Lutsker V, Scheid M, Jacquod P, Richter K. Spin transistor action from hidden Onsager reciprocity. PHYSICAL REVIEW LETTERS 2012; 108:236601. [PMID: 23003980 DOI: 10.1103/physrevlett.108.236601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Indexed: 06/01/2023]
Abstract
We investigate generic Hamiltonians for confined electrons with weak inhomogeneous spin-orbit coupling. Using a local gauge transformation we show how the SU(2) Hamiltonian structure reduces to a U(1)×U(1) structure for spinless fermions in a fictitious orbital magnetic field, to leading order in the spin-orbit strength. Using an Onsager relation, we further show how the resulting spin conductance vanishes in a two-terminal setup, and how it is turned on by either weakly breaking time-reversal symmetry or opening additional transport terminals, thus allowing one to switch the generated spin current on or off. We numerically check our theory for mesoscopic cavities as well as Aharonov-Bohm rings.
Collapse
Affiliation(s)
- İ Adagideli
- Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, Istanbul, Turkey
| | | | | | | | | |
Collapse
|
15
|
McCann E, Fal'ko VI. z→-z symmetry of spin-orbit coupling and weak localization in graphene. PHYSICAL REVIEW LETTERS 2012; 108:166606. [PMID: 22680746 DOI: 10.1103/physrevlett.108.166606] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Indexed: 06/01/2023]
Abstract
We show that the influence of spin-orbit (SO) coupling on the weak-localization effect for electrons in graphene depends on the lack or presence of z→-z symmetry in the system. While, for z→-z asymmetric SO coupling, disordered graphene should display a weak antilocalization behavior at lowest temperature, z→-z symmetric coupling leads to an effective saturation of decoherence time which can be partially lifted by an in-plane magnetic field, thus tending to restore the weak-localization effect.
Collapse
Affiliation(s)
- Edward McCann
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, United Kingdom
| | | |
Collapse
|
16
|
Valín-Rodríguez M. Predicted signatures of the intrinsic spin Hall effect in closed systems. PHYSICAL REVIEW LETTERS 2011; 107:266801. [PMID: 22243174 DOI: 10.1103/physrevlett.107.266801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Indexed: 05/31/2023]
Abstract
We study a two-dimensional electron system in the presence of spin-orbit interaction. It is shown analytically that the spin-orbit interaction acts as a transversal effective electric field, whose orientation depends on the sign of the z-axis spin projection. This effect does not require any driving electrical field and is inherent to the spin-orbit interactions present in semiconductor materials. Therefore, it should manifest in both closed and open systems. An experiment is proposed to observe the intrinsic spin Hall effect in the far infrared absorption of an asymmetric semiconductor nanostructure.
Collapse
Affiliation(s)
- Manuel Valín-Rodríguez
- Conselleria d'Educació i Cultura, Govern de les Illes Balears, 07004 Palma de Mallorca, Spain
| |
Collapse
|
17
|
Baruffa F, Stano P, Fabian J. Theory of anisotropic exchange in laterally coupled quantum dots. PHYSICAL REVIEW LETTERS 2010; 104:126401. [PMID: 20366552 DOI: 10.1103/physrevlett.104.126401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Indexed: 05/29/2023]
Abstract
The effects of spin-orbit coupling on the two-electron spectra in lateral coupled quantum dots are investigated analytically and numerically. It is demonstrated that in the absence of magnetic field, the exchange interaction is practically unaffected by spin-orbit coupling, for any interdot coupling, boosting prospects for spin-based quantum computing. The anisotropic exchange appears at finite magnetic fields. A numerically accurate effective spin Hamiltonian for modeling spin-orbit-induced two-electron spin dynamics in the presence of magnetic field is proposed.
Collapse
Affiliation(s)
- Fabio Baruffa
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | | | | |
Collapse
|
18
|
Scheid M, Kohda M, Kunihashi Y, Richter K, Nitta J. All-electrical detection of the relative strength of Rashba and Dresselhaus spin-orbit interaction in quantum wires. PHYSICAL REVIEW LETTERS 2008; 101:266401. [PMID: 19113779 DOI: 10.1103/physrevlett.101.266401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Indexed: 05/27/2023]
Abstract
We propose a method to determine the relative strength of Rashba and Dresselhaus spin-orbit interaction from transport measurements without the need of fitting parameters. To this end, we make use of the conductance anisotropy in narrow quantum wires with respect to the directions of an in-plane magnetic field, the quantum wire, and the crystal orientation. We support our proposal by numerical calculations of the conductance of quantum wires based on the Landauer formalism which show the applicability of the method to a wide range of parameters.
Collapse
Affiliation(s)
- Matthias Scheid
- Graduate School of Engineering, Tohoku University, 6-6-02 Aramaki-Aza Aoba, Aoba-ku, Sendai 980-8579, Japan.
| | | | | | | | | |
Collapse
|
19
|
Duckheim M, Loss D. Mesoscopic fluctuations in the spin-electric susceptibility due to Rashba spin-orbit interaction. PHYSICAL REVIEW LETTERS 2008; 101:226602. [PMID: 19113500 DOI: 10.1103/physrevlett.101.226602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Indexed: 05/27/2023]
Abstract
We investigate mesoscopic fluctuations in the spin polarization generated by a static electric field and by Rashba spin-orbit interaction in a disordered 2D electron gas. In a diagrammatic approach we find that the out-of-plane polarization--while being zero for self-averaging systems--exhibits large sample-to-sample fluctuations which are shown to be well within experimental reach. We evaluate the disorder-averaged variance of the susceptibility and find its dependence on magnetic field, spin-orbit interaction, dephasing, and chemical potential difference.
Collapse
Affiliation(s)
- Mathias Duckheim
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | | |
Collapse
|
20
|
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.
Collapse
|
21
|
Krich JJ, Halperin BI. Cubic Dresselhaus spin-orbit coupling in 2D electron quantum dots. PHYSICAL REVIEW LETTERS 2007; 98:226802. [PMID: 17677870 DOI: 10.1103/physrevlett.98.226802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Indexed: 05/16/2023]
Abstract
We study effects of the oft-neglected cubic Dresselhaus spin-orbit coupling (i.e., directly proportional p3) in GaAs/AlGaAs quantum dots. Using a semiclassical billiard model, we estimate the magnitude of the spin-orbit induced avoided crossings in a closed quantum dot in a Zeeman field. Using previous analyses based on random matrix theory, we calculate corresponding effects on the conductance through an open quantum dot. Combining our results with an experiment on an 8 microm2 quantum dot [D. M. Zumbühl, Phys. Rev. B 72, 081305 (2005)10.1103/PhysRevB.72.081305] suggests that (1) the GaAs Dresselhaus coupling constant gamma is approximately 9 eV A3, significantly less than the commonly cited value of 27.5 eV A3, and (2) the majority of the spin-flip effects can come from the cubic Dresselhaus term.
Collapse
Affiliation(s)
- Jacob J Krich
- Physics Department, Harvard University, Cambridge, Massachusetts 02138, USA
| | | |
Collapse
|
22
|
Bardarson JH, Adagideli I, Jacquod P. Mesoscopic spin Hall effect. PHYSICAL REVIEW LETTERS 2007; 98:196601. [PMID: 17677643 DOI: 10.1103/physrevlett.98.196601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Indexed: 05/16/2023]
Abstract
We investigate the spin Hall effect in ballistic chaotic quantum dots with spin-orbit coupling. We show that a longitudinal charge current can generate a pure transverse spin current. While this transverse spin current is generically nonzero for a fixed sample, we show that when the spin-orbit coupling time is short compared to the mean dwell time inside the dot, it fluctuates universally from sample to sample or upon variation of the chemical potential with a vanishing average.
Collapse
Affiliation(s)
- J H Bardarson
- Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands
| | | | | |
Collapse
|
23
|
Marinescu DC. Electron-dephasing time in a two-dimensional spin-polarized system with Rashba spin-orbit interaction. PHYSICAL REVIEW LETTERS 2006; 97:176802. [PMID: 17155492 DOI: 10.1103/physrevlett.97.176802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Indexed: 05/12/2023]
Abstract
We calculate the dephasing time tau(phi)(B) of an electron in a two-dimensional system with a Rashba spin-orbit interaction, spin-polarized by an arbitrarily large magnetic field parallel to the layer. tau(phi)(B) is estimated from the logarithmic corrections to the conductivity within a perturbative approach that assumes weak, isotropic disorder scattering. For any value of the magnetic field, the dephasing rate changes with respect to its unpolarized-state value by a universal function whose parameter is 2E(Z)/E(SOI) (E(Z) is the Zeeman energy, while E(SOI) is the spin-orbit interaction), confirming the experimental report published in Phys. Rev. Lett. 94, 186805 (2005). In the high-field limit, when 2E(Z) >> E(SOI), the dephasing rate saturates and reaches asymptotically to a value equal to half the spin-relaxation rate.
Collapse
Affiliation(s)
- D C Marinescu
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| |
Collapse
|
24
|
Stano P, Fabian J. Theory of phonon-induced spin relaxation in laterally coupled quantum dots. PHYSICAL REVIEW LETTERS 2006; 96:186602. [PMID: 16712384 DOI: 10.1103/physrevlett.96.186602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Indexed: 05/09/2023]
Abstract
Phonon-induced spin relaxation in coupled lateral quantum dots in the presence of spin-orbit coupling is calculated. The calculation for single dots is consistent with experiment. Spin relaxation in double dots at useful interdot couplings is dominated by spin-hot spots that are strongly anisotropic. Spin-hot spots are ineffective for a diagonal crystallographic orientation of the dots with a transverse in-plane field. This geometry is proposed for spin-based quantum information processing.
Collapse
Affiliation(s)
- Peter Stano
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | | |
Collapse
|
25
|
Punnoose A, Finkel'stein AM. Spin relaxation in the presence of electron-electron interactions. PHYSICAL REVIEW LETTERS 2006; 96:057202. [PMID: 16486973 DOI: 10.1103/physrevlett.96.057202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Indexed: 05/06/2023]
Abstract
The D'yakonov-Perel' spin relaxation induced by the spin-orbit interaction is examined in disordered two-dimensional electron gas. It is shown that, because of the electron-electron interactions, substantially different spin relaxation rates may be observed depending on the technique used to extract them. It is demonstrated that the relaxation rate of a spin population is proportional to the spin-diffusion constant D(s), while the spin-orbit scattering rate controlling the weak-localization corrections is proportional to the diffusion constant D, i.e., the conductivity. The two diffusion constants get strongly renormalized by the electron-electron interactions, but in different ways. As a result, the corresponding relaxation rates are different, with the difference between the two being especially strong near a magnetic instability or near the metal-insulator transition.
Collapse
|
26
|
Fal'ko VI, Altshuler BL, Tsyplyatyev O. Anisotropy of spin splitting and spin relaxation in lateral quantum dots. PHYSICAL REVIEW LETTERS 2005; 95:076603. [PMID: 16196808 DOI: 10.1103/physrevlett.95.076603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2005] [Indexed: 05/04/2023]
Abstract
Inelastic spin relaxation and spin splitting epsilon(s) in lateral quantum dots are studied in the regime of strong in-plane magnetic field. Because of both the g-factor energy dependence and spin-orbit coupling, epsilon(s) demonstrates a substantial nonlinear magnetic field dependence similar to that observed by Hanson et al. [Phys. Rev. Lett. 91, 196802 (2003)]. It also varies with the in-plane orientation of the magnetic field due to crystalline anisotropy of the spin-orbit coupling. The spin relaxation rate is also anisotropic, the anisotropy increasing with the field. When the magnetic length is less than the "thickness" of the GaAs dot, the relaxation can be an order of magnitude faster for B ||[100] than for B || [110].
Collapse
|
27
|
Ghosh A, Wright MH, Siegert C, Pepper M, Farrer I, Ford CJB, Ritchie DA. Zero-bias anomaly and kondo-assisted quasiballistic 2D transport. PHYSICAL REVIEW LETTERS 2005; 95:066603. [PMID: 16090970 DOI: 10.1103/physrevlett.95.066603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Revised: 04/18/2005] [Indexed: 05/03/2023]
Abstract
Nonequilibrium transport measurements in mesoscopic quasiballistic 2D electron systems show an enhancement in the differential conductance around the Fermi energy. At very low temperatures, such a zero-bias anomaly splits, leading to a suppression of linear transport at low energies. We also observed a scaling of the nonequilibrium characteristics at low energies which resembles electron scattering by two-state systems, addressed in the framework of two-channel Kondo model. Detailed sample-to-sample reproducibility indicates an intrinsic phenomenon in unconfined 2D systems in the low electron-density regime.
Collapse
Affiliation(s)
- A Ghosh
- Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom
| | | | | | | | | | | | | |
Collapse
|
28
|
Debald S, Emary C. Spin-orbit-driven coherent oscillations in a few-electron quantum dot. PHYSICAL REVIEW LETTERS 2005; 94:226803. [PMID: 16090425 DOI: 10.1103/physrevlett.94.226803] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2004] [Indexed: 05/03/2023]
Abstract
We propose an experiment to observe coherent oscillations in a single quantum dot with the oscillations driven by spin-orbit interaction. This is achieved without spin-polarized leads, and relies on changing the strength of the spin-orbit coupling via an applied gate pulse. We derive an effective model of this system which is formally equivalent to the Jaynes-Cummings model of quantum optics. For parameters relevant to an InGaAs dot, we calculate a Rabi frequency of 2 GHz.
Collapse
Affiliation(s)
- Stefan Debald
- Institut für Theoretische Physik, Universität Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany
| | | |
Collapse
|
29
|
Könemann J, Haug RJ, Maude DK, Fal'ko VI, Altshuler BL. Spin-orbit coupling and anisotropy of spin splitting in quantum dots. PHYSICAL REVIEW LETTERS 2005; 94:226404. [PMID: 16090418 DOI: 10.1103/physrevlett.94.226404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Indexed: 05/03/2023]
Abstract
In lateral quantum dots, the combined effect of both Dresselhaus and Bychkov-Rashba spin-orbit coupling is equivalent to an effective magnetic field +/- B(SO) which has the opposite sign for s(z)= +/- 1/2 spin electrons. When the external magnetic field is perpendicular to the planar structure, the field B(SO) generates an additional splitting for electron states as compared to the spin splitting in the in-plane field orientation. The anisotropy of spin splitting has been measured and then analyzed in terms of spin-orbit coupling in several AlGaAs/GaAs quantum dots by means of resonant tunneling spectroscopy. From the measured values and sign of the anisotropy we are able to determine the dominating spin-orbit coupling mechanism.
Collapse
Affiliation(s)
- J Könemann
- Institut für Festkörperphysik, Universität Hannover, Appelstrasse 2, D-30167 Hannover, Germany
| | | | | | | | | |
Collapse
|
30
|
Meijer FE, Morpurgo AF, Klapwijk TM, Nitta J. Universal spin-induced time reversal symmetry breaking in two-dimensional electron gases with Rashba spin-orbit interaction. PHYSICAL REVIEW LETTERS 2005; 94:186805. [PMID: 15904395 DOI: 10.1103/physrevlett.94.186805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2004] [Indexed: 05/02/2023]
Abstract
We have experimentally studied the spin-induced time reversal symmetry (TRS) breaking as a function of the relative strength of the Zeeman energy (E(Z)) and the Rashba spin-orbit interaction energy (E(SOI)), in InGaAs-based 2D electron gases. We find that the TRS breaking, and hence the associated dephasing time tau(phi)(B), saturates when E(Z) becomes comparable to E(SOI). Moreover, we show that the spin-induced TRS breaking mechanism is a universal function of the ratio E(Z)/E(SOI), within the experimental accuracy.
Collapse
Affiliation(s)
- F E Meijer
- Kavli Institute of NanoScience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
| | | | | | | |
Collapse
|
31
|
Affiliation(s)
- Prashant Sharma
- Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA.
| |
Collapse
|
32
|
Zaitsev O, Frustaglia D, Richter K. Role of orbital dynamics in spin relaxation and weak antilocalization in quantum dots. PHYSICAL REVIEW LETTERS 2005; 94:026809. [PMID: 15698215 DOI: 10.1103/physrevlett.94.026809] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Indexed: 05/24/2023]
Abstract
We develop a semiclassical theory for spin-dependent quantum transport to describe weak (anti)localization in quantum dots with spin-orbit coupling. This allows us to distinguish different types of spin relaxation in systems with chaotic, regular, and diffusive orbital classical dynamics. We find, in particular, that for typical Rashba spin-orbit coupling strengths, integrable ballistic systems can exhibit weak localization, while corresponding chaotic systems show weak antilocalization. We further calculate the magnetoconductance and analyze how the weak antilocalization is suppressed with decreasing quantum dot size and increasing additional in-plane magnetic field.
Collapse
Affiliation(s)
- Oleg Zaitsev
- Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany.
| | | | | |
Collapse
|
33
|
Rokhinson LP, Larkina V, Lyanda-Geller YB, Pfeiffer LN, West KW. Spin separation in cyclotron motion. PHYSICAL REVIEW LETTERS 2004; 93:146601. [PMID: 15524823 DOI: 10.1103/physrevlett.93.146601] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Indexed: 05/24/2023]
Abstract
Charged carriers with different spin states are spatially separated in a two-dimensional hole gas. Because of strong spin-orbit interaction, holes at the Fermi energy in GaAs have different momenta for two possible spin states traveling in the same direction, and, correspondingly, different cyclotron orbits in a weak magnetic field. Two point contacts, acting as a monochromatic source of ballistic holes and a narrow detector arranged in the magnetic focusing geometry are demonstrated to work as a tunable spin filter.
Collapse
Affiliation(s)
- L P Rokhinson
- Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA.
| | | | | | | | | |
Collapse
|
34
|
Sharma P, Brouwer PW. Mesoscopic effects in adiabatic spin pumping. PHYSICAL REVIEW LETTERS 2003; 91:166801. [PMID: 14611425 DOI: 10.1103/physrevlett.91.166801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2003] [Indexed: 05/24/2023]
Abstract
We show that temporal shape modulations (pumping) of a quantum dot in the presence of spin-orbital coupling lead to a finite dc spin current. Depending on the strength of the spin-orbit coupling, the spin current is polarized perpendicular to the plane of the two-dimensional electron gas, or has an arbitrary direction subject to mesoscopic fluctuations. We analyze the statistics of the spin and charge currents in the adiabatic limit for the full crossover from weak to strong spin-orbit coupling.
Collapse
Affiliation(s)
- Prashant Sharma
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501, USA
| | | |
Collapse
|
35
|
Held K, Eisenberg E, Altshuler BL. Random matrix theory for closed quantum dots with weak spin-orbit coupling. PHYSICAL REVIEW LETTERS 2003; 90:106802. [PMID: 12689023 DOI: 10.1103/physrevlett.90.106802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2002] [Indexed: 05/24/2023]
Abstract
To lowest order in the coupling strength, the spin-orbit coupling in quantum dots results in a spin-dependent Aharonov-Bohm flux. This flux decouples the spin-up and spin-down random matrix theory ensembles of the quantum dot. We employ this ensemble and find significant changes in the distribution of the Coulomb blockade peak height, in particular, a decrease of the width of the distribution. The puzzling disagreement between standard random matrix theory and the experimental distributions by Patel et al. [Phys. Rev. Lett. 81, 5900 (1998)]] might possibly be attributed to these spin-orbit effects.
Collapse
Affiliation(s)
- K Held
- Physics Department, Princeton University, Princeton, New Jersey 08544, USA.
| | | | | |
Collapse
|
36
|
Miller JB, Zumbühl DM, Marcus CM, Lyanda-Geller YB, Goldhaber-Gordon D, Campman K, Gossard AC. Gate-controlled spin-orbit quantum interference effects in lateral transport. PHYSICAL REVIEW LETTERS 2003; 90:076807. [PMID: 12633263 DOI: 10.1103/physrevlett.90.076807] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2002] [Indexed: 05/24/2023]
Abstract
In situ control of spin-orbit coupling in coherent transport using a clean GaAs/AlGaAs two-dimensional electron gas is realized, leading to a gate-tunable crossover from weak localization to antilocalization. The necessary theory of 2D magnetotransport in the presence of spin-orbit coupling beyond the diffusive approximation is developed and used to analyze experimental data. With this theory the Rashba contribution and linear and cubic Dresselhaus contributions to spin-orbit coupling are separately estimated, allowing the angular dependence of spin-orbit precession to be extracted at various gate voltages.
Collapse
Affiliation(s)
- J B Miller
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | | | | | | | | | | | | |
Collapse
|
37
|
Zumbühl DM, Miller JB, Marcus CM, Campman K, Gossard AC. Spin-orbit coupling, antilocalization, and parallel magnetic fields in quantum dots. PHYSICAL REVIEW LETTERS 2002; 89:276803. [PMID: 12513231 DOI: 10.1103/physrevlett.89.276803] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2002] [Indexed: 05/24/2023]
Abstract
We investigate antilocalization due to spin-orbit coupling in ballistic GaAs quantum dots. Antilocalization that is prominent in large dots is suppressed in small dots, as anticipated theoretically. Parallel magnetic fields suppress both antilocalization and also, at larger fields, weak localization, consistent with random matrix theory results once orbital coupling of the parallel field is included. In situ control of spin-orbit coupling in dots is demonstrated as a gate-controlled crossover from weak localization to antilocalization.
Collapse
Affiliation(s)
- D M Zumbühl
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | | | | | | | | |
Collapse
|
38
|
Governale M. Quantum dots with Rashba spin-orbit coupling. PHYSICAL REVIEW LETTERS 2002; 89:206802. [PMID: 12443496 DOI: 10.1103/physrevlett.89.206802] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2002] [Indexed: 05/24/2023]
Abstract
We present results on the effects of spin-orbit coupling on the electronic structure of few-electron interacting quantum dots. The ground-state properties as a function of the number of electrons in the dot N are calculated by means of spin-density functional theory. We find a suppression of Hund's rule due to the competition of the Rashba effect and exchange interaction. Introducing an in-plane Zeeman field leads to a paramagnetic behavior of the dot in a closed-shell configuration and to spin texture in space.
Collapse
Affiliation(s)
- M Governale
- Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany
| |
Collapse
|
39
|
Mucciolo ER, Chamon C, Marcus CM. Adiabatic quantum pump of spin-polarized current. PHYSICAL REVIEW LETTERS 2002; 89:146802. [PMID: 12366064 DOI: 10.1103/physrevlett.89.146802] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2001] [Indexed: 05/23/2023]
Abstract
We propose a mechanism by which an open quantum dot driven by two ac (radio frequency) gate voltages in the presence of a moderate in-plane magnetic field generates a spin-polarized, phase-coherent dc current. The idea combines adiabatic, nonquantized (but coherent) pumping through periodically modulated external parameters and the strong fluctuations of the electron wave function existent in chaotic cavities. We estimate that the spin polarization of the current can be observed for temperatures and Zeeman splitting energies of the order of the single-particle mean level spacing.
Collapse
Affiliation(s)
- Eduardo R Mucciolo
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, C.P. 38071, 22452-970 Rio de Janeiro, Brazil
| | | | | |
Collapse
|
40
|
Apalkov VM, Raikh ME. Zero-field satellites of a zero-bias anomaly. PHYSICAL REVIEW LETTERS 2002; 89:096805. [PMID: 12190428 DOI: 10.1103/physrevlett.89.096805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2002] [Indexed: 05/23/2023]
Abstract
Spin-orbit (SO) splitting, +/-omega(SO), of the electron Fermi surface in two-dimensional systems manifests itself in the interaction-induced corrections to the tunneling density of states, nu(epsilon). Namely, in the case of a smooth disorder, it gives rise to the satellites of a zero-bias anomaly at energies epsilon = +/-2 omega(SO). Zeeman splitting, +/-omega(Z), in a weak parallel magnetic field causes a narrow plateau of a width delta epsilon = 2 omega(Z) at the top of each sharp satellite peak. As omega(Z) exceeds omega(SO), the SO satellites cross over to the conventional narrow maxima at epsilon = +/-2 omega(Z) with SO-induced plateaus delta epsilon = 2 omega(SO) at the tops.
Collapse
Affiliation(s)
- V M Apalkov
- Department of Physics, University of Utah, Salt Lake City, Utah 84112, USA
| | | |
Collapse
|
41
|
Alves ERP, Lewenkopf CH. Conductance fluctuations and weak localization in chaotic quantum dots. PHYSICAL REVIEW LETTERS 2002; 88:256805. [PMID: 12097114 DOI: 10.1103/physrevlett.88.256805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2001] [Indexed: 05/23/2023]
Abstract
We study the conductance statistical features of ballistic electrons flowing through a chaotic quantum dot. We show how the temperature affects the universal conductance fluctuations by analyzing the influence of dephasing and thermal smearing. This leads us to two main findings. First, we show that the energy correlations in the transmission, which were overlooked so far, are important for calculating the variance and higher moments of the conductance. Second, we show that there is an ambiguity in the method of determination of the dephasing rate from the size of the weak localization. We find that the dephasing times obtained at low temperatures from quantum dots are underestimated.
Collapse
Affiliation(s)
- E R P Alves
- Instituto de Física, Universidade do Estado do Rio de Janeiro, R. São Francisco Xavier, 524, 20559-900 Rio de Janeiro, Brazil
| | | |
Collapse
|