Doped moir\'e magnets: renormalized flat bands and excitonic phases

TL;DR

This paper investigates the complex phase diagram of doped twisted bilayer honeycomb lattices, revealing new excitonic insulating phases and the impact of interactions on flat band features using slave boson mean-field theory.

Contribution

It introduces a theoretical analysis of doped moiré magnets, uncovering novel excitonic phases and interaction-dependent flat band phenomena in twisted bilayer systems.

Findings

Discovery of a non-magnetic excitonic insulating phase.

Interaction effects significantly alter magic angles and band dispersion.

Rich phase diagram with various emergent phases depending on doping and twist angle.

Abstract

We explore the phase diagram of a twisted bilayer of strongly interacting electrons on a honeycomb lattice close to half-filling using the slave boson mean-field theory. Our analysis indicates that a variety of new phases can be realized as a function of chemical doping and twist angle. In particular, we find a non-magnetic excitonic insulating phase that breaks the translational symmetry of the underlying moir\'e pattern. This phase results from the interplay of strong Coulomb interactions and the twist angle. In addition, we show that the features of the renormalized dispersion such as the magic angles depend significantly on the interactions. Our results highlight the rich physics arising in doped moir\'e superlattices of Mott insulators.