Generalized Onsager reciprocal relations of charge and spin transport

TL;DR

This paper extends Onsager reciprocal relations to charge and spin transport in systems that break time-reversal symmetry but preserve a combined symmetry, predicting new transport phenomena verified in cold atomic systems.

Contribution

It generalizes Onsager relations to systems with combined symmetries, broadening the understanding of charge and spin transport coupling.

Findings

Derived generalized Onsager relations for systems with combined symmetries.

Predicted novel transport phenomena in cold atomic systems.

Validated the theoretical framework with explicit model demonstrations.

Abstract

In spin-orbit-coupled systems the charge and spin transport are generally coupled to each other, namely a charge current will induce a spin current and vice versa. In the presence of time-reversal symmetry $T$, the cross-coupling transport coefficients describing how one process affects the other are constrained by the famous Onsager reciprocal relations. In this paper, we generalize the Onsager reciprocal relations of charge and spin transport to systems that break the time-reversal symmetry but preserve a combined symmetry of $T$ and some other symmetry operation $O$. We show that the symmetry or antisymmetry of the cross-coupling transport coefficients remains in place provided that the operator $O$ meets certain conditions. Among many candidate systems where our generalized Onsager relations apply, we focus on a conceptually simple and experimentally realized model in cold atomic systems for explicit demonstration and use these relations to predict highly non-trivial transport phenomena that can be readily verified experimentally.