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arXiv · 1705.08898

Covariant conservation laws and the spin Hall effect in Dirac-Rashba systems

Mirco Milletari·Manuel Offidani·Aires Ferreira·Roberto Raimondi
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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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Mirco Milletari, Manuel Offidani, Aires Ferreira, Roberto Raimondi. 2017-12-20. Covariant conservation laws and the spin Hall effect in Dirac-Rashba systems. https://doi.org/10.1103/physrevlett.119.246801

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