Influence of impurity spin dynamics on quantum transport in epitaxial graphene

TL;DR

This study investigates how impurity spin dynamics influence quantum transport in epitaxial graphene, revealing that in-plane magnetic fields can suppress spin relaxation caused by spinful scatterers, affecting conductivity interference effects.

Contribution

It demonstrates the impact of impurity spin dynamics on quantum transport in epitaxial graphene and uncovers the non-monotonic behavior of decoherence rates under magnetic fields.

Findings

Spin relaxation is suppressed by in-plane magnetic fields.

Spinful scatterers significantly contribute to spin relaxation.

Non-monotonic dependence of decoherence rate on magnetic field.

Abstract

Experimental evidence from both spin-valve and quantum transport measurements points towards unexpectedly fast spin relaxation in graphene. We report magnetotransport studies of epitaxial graphene on SiC in a vector magnetic field showing that spin relaxation, detected using weak-localisation analysis, is suppressed by an in-plane magnetic field, $B_{\parallel}$, and thereby proving that it is caused at least in part by spinful scatterers. A non-monotonic dependence of effective decoherence rate on $B_{\parallel}$ reveals the intricate role of scatterers' spin dynamics in forming the interference correction to conductivity, an effect that has gone unnoticed in earlier weak localisation studies