Effect of uniaxial strain on ferromagnetic instability and formation of localized magnetic states on adatoms in graphene

We investigate the effect of an applied uniaxial strain on the ferromagnetic instability due to long-range Coulomb interaction between Dirac fermions in graphene. In the case of undeformed graphene the ferromagnetic exchange instability occurs at sufficiently strong interaction within the Hartree-Fock approximation. In this work we show that using the same theoretical framework but with an additional applied uniaxial strain, the transition can occur for much weaker interaction, within the range in suspended graphene. We also study the consequence of strain on the formation of localized magnetic states on adatoms in graphene. We systematically analyze the interplay between the anisotropic (strain-induced) nature of the Dirac fermions in graphene, onsite Hubbard interaction at the impurity, and the hybridization between the graphene and impurity electrons. The polarization of the electrons in the localized orbital is numerically calculated within the mean-field self-consistent scheme. We obtain a complete phase diagram containing nonmagnetic as well as magnetic regions, and our results can find prospective application in the field of carbon-based spintronics. DOI: 10.1103/PhysRevB.87.155431