Functional renormalization group and variational Monte Carlo studies of the electronic instabilities in graphene near14doping

Abstract

We study the electronic instabilities of near 1/4 electron doped graphene using the singular-mode functional renormalization group, with a self-adaptive $k$ mesh to improve the treatment of the van Hove singularities, and variational Monte Carlo method. At 1/4 doping the system is a chiral spin-density wave state exhibiting the anomalous quantized Hall effect. When the doping deviates from 1/4, the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}+i{d}_{xy}$ Cooper pairing becomes the leading instability. Our results suggest that near 1/4 electron or hole doping (away from the neutral point) the graphene is either a Chern insulator or a topoligical superconductor.