Disorder-perturbed Landau levels in high-electron-mobility epitaxial graphene

Abstract

International audienceWe show that the Landau levels in epitaxial graphene in the presence of localized defects are significantly modified compared to those of an ideal system. We report on magnetospectroscopy experiments performed on high-quality samples. Besides typical interband magneto-optical transitions, we clearly observe additional transitions that involve perturbed states associated with short-range impurities such as vacancies. Their intensity is found to decrease with an annealing process and a partial self-healing over time is observed. Calculations of the perturbed Landau levels by using a delta-like potential show electronic states both between and at the same energies as the Laudau levels of ideal graphene. The calculated absorption spectra involving all perturbed and unperturbed states are in very good agreement with the experiments