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Spin injection beyond the diffusive limit in the presence of spin-orbit coupling

Lennart-Knud Liefeith, Rajkiran Tholapi, Tomotsugu Ishikura, Max Hänze, Robert Hartmann, Taras Slobodskyy, and Wolfgang Hansen
Phys. Rev. B 95, 081303(R) – Published 27 February 2017

Abstract

Spin injection from epitaxial iron into InGaAs/InAs quantum wells is observed using an all-electric nonlocal setup. From the choice of material, a significant spin-orbit interaction (SOI) is expected. The contact separation of the spin-valve devices is in the order of the mean free path so that the transport is at the transition between diffusive and ballistic. With an established purely diffusive model a spin-injection efficiency of 77% is determined from the data. This value is very large compared to previous observations on diffusive spin-valve devices on similar material systems. Motivated by similar results on ballistic spin-valve devices in a material system with small spin-orbit coupling, a recent model was suggested in which a ballistic spin-dephasing length was pointed out to be the crucial length scale. With this model and an experimentally determined spin-orbit coupling parameter of α=4×1012 eV m, very high spin-injection efficiencies are still determined in our quantum wells. We suggest that the spin-dephasing length to be used in the model must be larger due to the crystallographic anisotropy of the spin-orbit coupling, i.e., in our setup the SOI stabilizes the spin in the crystal direction of the spin-polarized current.

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  • Received 7 October 2016
  • Revised 19 December 2016

DOI:https://doi.org/10.1103/PhysRevB.95.081303

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Lennart-Knud Liefeith1,*, Rajkiran Tholapi1, Tomotsugu Ishikura2, Max Hänze1, Robert Hartmann1, Taras Slobodskyy1, and Wolfgang Hansen1

  • 1Institut für Nanostruktur- und Festkörperphysik, Universität Hamburg, 20355 Hamburg, Germany
  • 2Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, Sapporo 060-8628, Japan

  • *lliefeit@physnet.uni-hamburg.de

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Issue

Vol. 95, Iss. 8 — 15 February 2017

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