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-localization analysis, is suppressed by an in-plane magnetic field B-parallel to, and thereby proving that it is caused at least in part by spinful scatterers. A nonmonotonic dependence of the effective decoherence rate on B-parallel to reveals the intricate role of the scatterers spin dynamics in forming the interference correction to the conductivity, an effect that has gone unnoticed in earlier weak localization studies. Funding Agencies|NSERC; CFI; Quantum Matter Institute (QMI); EC Graphene Flagship [CNECT-ICT-604391]; European Metrology Research Program (EMRP) project GraphOhm; ERC Synergy Grant Hetero2D; Deutsche Forschungsgemeinschaft [GRK 1621]; Linnaeus Centre for Quantum Engineering; Swedish Research Council; Knut and Alice Wallenberg Foundation; Swedish Foundation for Strategic Research (SSF); Chalmers Area of Advance NANO