Interaction-induced enhancement of g factor in graphene

Abstract

We study the effect of electron interaction on the spin splitting and the g factor in graphene in a perpendicular magnetic field using the Hartree and the Hubbard approximations within the Thomas-Fermi model. We found that the effective g factor is enhanced in comparison to its free-electron value g=2 and oscillates as a function of the filling factor ν in the range 2≤g*¢ 4 reaching maxima at ν=4N=0,±4,±8,... and minima at ν=4N+12=±2,±6,±10,..., with N being the Landau level index. We outline the role of charged impurities in the substrate, which are shown to suppress the oscillations of the g * factor. This effect becomes especially pronounced with the increase of the impurity concentration, when the effective g factor becomes independent of the filling factor, reaching a value of g*2.3. A relation to the recent experiment is discussed. © 2012 American Physical Society.