Anomalous Hall effect in 2D Dirac materials

TL;DR

This paper develops a unified theory for charge transport in 2D Dirac materials with broken symmetries, revealing a robust anomalous Hall effect and a tunable extrinsic spin Hall effect driven by spin-orbit interactions and gate voltage.

Contribution

It introduces a comprehensive theoretical framework explaining anomalous and spin Hall effects in 2D Dirac systems with broken symmetries, highlighting new mechanisms and tunability.

Findings

Gate voltage causes sign change in anomalous Hall conductivity.

Robustness of the effect against impurity scattering.

Discovery of a tunable extrinsic spin Hall effect.

Abstract

We present a unified theory of charge carrier transport in 2D Dirac systems with broken mirror inversion and time-reversal symmetries (e.g., as realized in ferromagnetic graphene). We find that the entanglement between spin and pseudospin SU(2) degrees of freedom stemming from spin-orbit effects leads to a distinctive gate voltage dependence (change of sign) of the anomalous Hall conductivity approaching the topological gap, which remains robust against impurity scattering and thus is a smoking gun for magnetized 2D Dirac fermions. Furthermore, we unveil a robust skew scattering mechanism, modulated by the spin texture of the energy bands, which causes a net spin accumulation at the sample boundaries even for spin-transparent disorder. The newly unveiled extrinsic spin Hall effect is readily tunable by a gate voltage and opens novel opportunities for the control of spin currents in 2D ferromagnetic materials.