Temperature dependence of electron density and electron–electron interactions in monolayer epitaxial graphene grown on SiC

Abstract

We report carrier density measurements and electron–electron (e–e) interactions in monolayer epitaxial graphene grown on SiC. The temperature (T)-independent carrier density determined from the Shubnikov–de Haas (SdH) oscillations clearly demonstrates that the observed logarithmic temperature dependence of the Hall slope in our system must be due to e–e interactions. Since the electron density determined from conventional SdH measurements does not depend on e–e interactions based on Kohn’s theorem, SdH experiments appear to be more reliable compared with the classical Hall effect when one studies the T dependence of the carrier density in the low T regime. On the other hand, the logarithmic T dependence of the Hall slope δRxy/δB can be used to probe e–e interactions even when the conventional conductivity method is not applicable due to strong electron–phonon scattering.