Influence of impurity spin dynamics on quantum transport in epitaxial graphene

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