Spin-density-wave and nematicity in magic angle twisted bilayer graphene

by A. O. Sboychakov (Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, Moscow)

Thursday 7 Nov 2019, 14:30 → 16:00 Europe/Rome

Sala Lauree (Dip. di Fisica - Edificio G. Marconi)

We study the ground-state properties of twisted bilayer graphene. The low-energy single-electron spectrum consists of weakly dispersing partially degenerate bands, making electrons susceptible to the effects of interactions. Introducing several order parameters with spin-density-wave-like structure, we demonstrate that (i) the band degeneracy is partially lifted, and (ii) the low-energy spectrum becomes doping-dependent. Such sensitivity to doping allows us to reproduce qualitatively the behavior of the conductance observed in experiments. Near half-filling, the hexagonal symmetry is lost, and a nematic state appears, that is robust against variations of the interlayer hopping amplitude.