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.

Milletarã¬, M., Offidani, M., Ferreira, A., Raimondi, R. (2017). Covariant Conservation Laws and the Spin Hall Effect in Dirac-Rashba Systems. PHYSICAL REVIEW LETTERS, 119(24), 246801 [10.1103/PhysRevLett.119.246801].

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

Raimondi, Roberto
2017-01-01

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.
Milletarã¬, M., Offidani, M., Ferreira, A., Raimondi, R. (2017). Covariant Conservation Laws and the Spin Hall Effect in Dirac-Rashba Systems. PHYSICAL REVIEW LETTERS, 119(24), 246801 [10.1103/PhysRevLett.119.246801].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11590/326742
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