Predicting and understanding diffusion lengths and lifetimes in solids via a many-body \textit{ab initio} method: The role of coupled dynamics

TL;DR

This paper introduces an extit{ab initio} method for predicting diffusion lengths and lifetimes in solids by modeling coupled dynamical processes, providing insights into spin relaxation and diffusion in materials like graphene-hBN.

Contribution

The paper develops a novel extit{ab initio} approach that incorporates coupled dynamics to accurately predict diffusion lengths and lifetimes in solids, extending beyond traditional approximate formulas.

Findings

Coupled dynamics significantly influence spin diffusion and relaxation.

The method accurately describes long lifetimes and diffusion lengths in solids.

Application to graphene-hBN demonstrates the method's effectiveness.

Abstract

We present an \textit{ab initio} method of diffusion, relaxation and dephasing processes of arbitrary observables, and corresponding diffusion lengths and lifetimes in solids. The method is based on linearized density-matrix master equation, with quantum treatment of electron scattering processes. It enables clear \textit{ab initio} descriptions of long lifetimes and diffusion lengths using approximate formulas at different levels, such as Dyakonov-Perel and drift-diffusion relations for spin decay and those beyond with coupled dynamics. Our results of graphene-hBN show that the coupling between dynamical processes can significantly affect spin diffusion and relaxation. Our method provides a transparent and powerful tool for predicting and understanding diffusion and relaxation.