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

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 spincharge transport in graphene with interface-induced Bychkov-Rashba effect. The method makes use of a 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 slowly varying electric-and spin-injection fields 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.