Spin transport in epitaxial graphene on the C-terminated (0001)-face of silicon carbide

摘要

We performed a temperature dependent study of the charge and spin transport properties of epitaxial graphene on the C-terminated (0001) face of silicon carbide (SiC), a system without a carbon buffer layer between the graphene and the SiC. Using spin Hanle precession in the nonlocal geometry, we measured a spin relaxation length of λ_s = 0.7 μm at room temperature, lower than in exfoliated graphene. We show that the charge and spin diffusion coefficient, D_c and D_s, respectively, increasingly deviate from each other during electrical measurements up to a difference of a factor 4. Thus, we show that a model of localized states that was previously used to explain D_c≠D_s, can also be applied to epitaxial graphene systems without a carbon buffer layer. We attribute the effect to charge trap states in the interface between the graphene and the SiC.