Stochastic cRPA calculations of screened interactions in graphene moire states at high pressures

Twisted bilayer graphene (tBLG) hosts correlated electrons in flat bands, stemming from the coupling between mutually rotated monolayers. The coupling is primarily controlled by the twist angle but equally well by the bilayer’s in-plane strain or compression. It was found previously that under angle twist screening plays a crucial role in reducing bare Coulomb interactions as one approaches the magic angle. The pressure behavior of screening is however less investigated.

In this work [1], we apply the stochastic constrained random phase approximation to study the dynamical renormalization of electronic interactions in twisted bilayer graphene (tBLG) characterized by giant supercells cells with ~9000 electrons. We map the correlated subspace on a model Hamiltonian and study the interplay of screening and the on-site interaction at varying pressure. Our results show a striking difference for pressure dependence of screening compared to the previously computed twist angle dependence.