Mott correlations in ABC graphene trilayer aligned with hBN

Abstract

ABC trilayer graphene aligned with hexagonal boron nitride (ABC/hBN) and other moiré systems have shown insulating phases at integer fillings of the moiré lattice. The role of Mott physics in these insulating states has been questioned by observations of correlated states in a nonaligned ABC trilayer, but recent photocurrent experiments in aligned samples are consistent with the existence of a Mott insulating state at half filling. Using dynamical mean-field theory we address the effect of Mott correlations in ABC/hBN. We show that, at experimentally relevant interaction values, the electronic states are strongly affected by a significant spectral weight transfer not present without alignment to hBN. This effect, which emerges at interactions considerably smaller than UMott (at which the Mott metal-insulator transition takes place) and does not require symmetry breaking, also impacts the electronic properties at temperatures above the ordering transitions producing anomalous temperature and doping dependencies. Close to the Mott transition, the intramoiré unit cell interactions promote an antiferromagnetic state, probably breaking the C3 symmetry, that would compete with the ferromagnetic exchange interactions to determine the ground state.