Nonlinear spin current generation in noncentrosymmetric spin-orbit coupled systems

Keita Hamamoto, Motohiko Ezawa, Kun Woo Kim, Takahiro Morimoto, and Naoto Nagaosa
Phys. Rev. B 95, 224430 – Published 26 June 2017

Abstract

Spin current plays a central role in spintronics. In particular, finding more efficient ways to generate spin current has been an important issue and has been studied actively. For example, representative methods of spin-current generation include spin-polarized current injections from ferromagnetic metals, the spin Hall effect, and the spin battery. Here, we theoretically propose a mechanism of spin-current generation based on nonlinear phenomena. By using Boltzmann transport theory, we show that a simple application of the electric field E induces spin current proportional to E2 in noncentrosymmetric spin-orbit coupled systems. We demonstrate that the nonlinear spin current of the proposed mechanism is supported in the surface state of three-dimensional topological insulators and two-dimensional semiconductors with the Rashba and/or Dresselhaus interaction. In the latter case, the angular dependence of the nonlinear spin current can be manipulated by the direction of the electric field and by the ratio of the Rashba and Dresselhaus interactions. We find that the magnitude of the spin current largely exceeds those in the previous methods for a reasonable magnitude of the electric field. Furthermore, we show that application of ac electric fields (e.g., terahertz light) leads to the rectifying effect of the spin current, where dc spin current is generated. These findings will pave a route to manipulate the spin current in noncentrosymmetric crystals.

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  • Received 12 January 2017
  • Revised 30 May 2017

DOI:https://doi.org/10.1103/PhysRevB.95.224430

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Keita Hamamoto1, Motohiko Ezawa1, Kun Woo Kim2, Takahiro Morimoto3, and Naoto Nagaosa1,4

  • 1Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
  • 2School of Physics, Korea Institute for Advanced Study, Seoul 02455, Korea
  • 3Department of Physics, University of California, Berkeley, California 94720, USA
  • 4RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan

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Issue

Vol. 95, Iss. 22 — 1 June 2017

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