Covariant Conservation Laws and the Spin Hall Effect in Dirac-Rashba Systems

Mirco Milletarì, Manuel Offidani, Aires Ferreira, and Roberto Raimondi
Phys. Rev. Lett. 119, 246801 – Published 14 December 2017
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Abstract

We present a theoretical analysis of two-dimensional Dirac-Rashba systems in the presence of disorder and external perturbations. We unveil a set of exact symmetry relations (Ward identities) that impose strong constraints on the spin dynamics of Dirac fermions subject to proximity-induced interactions. This allows us to demonstrate that an arbitrary dilute concentration of scalar impurities results in the total suppression of nonequilibrium spin Hall currents when only Rashba spin-orbit coupling is present. Remarkably, a finite spin Hall conductivity is restored when the minimal Dirac-Rashba model is supplemented with a spin–valley interaction. The Ward identities provide a systematic way to predict the emergence of the spin Hall effect in a wider class of Dirac-Rashba systems of experimental relevance and represent an important benchmark for testing the validity of numerical methodologies.

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  • Received 25 May 2017

DOI:https://doi.org/10.1103/PhysRevLett.119.246801

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Mirco Milletarì*

  • Dipartimento di Matematica e Fisica, Università Roma Tre, 00146 Rome, Italy and Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore

Manuel Offidani and Aires Ferreira

  • Department of Physics, University of York, York YO10 5DD, United Kingdom

Roberto Raimondi

  • Dipartimento di Matematica e Fisica, Università Roma Tre, 00146 Rome, Italy

  • *milletari@gmail.com
  • aires.ferreira@york.ac.uk

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Issue

Vol. 119, Iss. 24 — 15 December 2017

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