Interplay between interferences and electron-electron interactions in epitaxial graphene

We separate localization and interaction effects in epitaxial graphene devices grown on the C face of an 8 degrees-off-axis 4H-SiC substrate by analyzing the low-temperature conductivities. Weak localization and antilocalization are extracted at low magnetic fields, after elimination of a geometric magnetoresistance and subtraction of the magnetic-field-dependent Drude conductivity. The electron-electron interaction correction is extracted at higher magnetic fields, where localization effects disappear. Both phenomena are weak but sizable and of the same order of magnitude. If compared to graphene on silicon dioxide, the electron-electron interactions on epitaxial graphene are not significantly reduced by the larger dielectric constant of the SiC substrate.