Theory of spin-charge-coupled transport in proximitized graphene: An SO(5) algebraic approach

TL;DR

This paper develops a unified quantum kinetic framework using SO(5) algebra to describe spin-charge coupled transport in proximitized graphene, enabling analysis of complex spin dynamics under various external conditions.

Contribution

It introduces an SO(5) algebraic extension of the inverse-diffuson method to derive a comprehensive set of drift-diffusion equations for spin-charge transport in graphene.

Findings

Derived a quantum kinetic equation treating spin and pseudospin equally.

Formulated drift-diffusion equations for proximitized graphene with impurities.

Applicable to layered materials with strong spin-valley coupling.

Abstract

Establishing the conditions under which orbital, spin and lattice-pseudospin degrees of freedom are mutually coupled in realistic nonequilibrium conditions is a major goal in the emergent field of graphene spintronics. Here, we use linear-response theory to obtain a unified microscopic description of spin dynamics and coupled spin-charge transport in graphene with an interface-induced Bychkov-Rashba effect. Our method makes use of an SO(5) extension of the familiar inverse-diffuson approach to obtain a quantum kinetic equation for the single-particle density matrix that treats spin and pseudospin on equal footing and is valid for arbitrary external perturbations. As an application of the formalism, we derive a complete set of drift-diffusion equations for proximitized graphene with scalar impurities in the presence of electric and spin-injection fields which vary slowly in space and time. Our approach is amenable to a wide variety of generalizations, including the study of coupled spin-charge dynamics in layered materials with strong spin-valley coupling and spin-orbit torques in van der Waals heterostructures.