Moiré-Bose-Hubbard model for interlayer excitons in twisted transition metal dichalcogenide heterostructures

Abstract

In bilayers of semiconducting transition metal dichalcogenides, the twist angle between layers can be used to introduce a highly regular periodic potential modulation on a length scale that is large compared to the unit cell. In such structures, correlated states can emerge, in which excitons in the heterostructure are strongly localized to the potential minima due to exciton-exciton interactions. We explore the transition between Mott and extended exciton phases in terms of a moiré-Bose-Hubbard Hamiltonian. Hopping and on-site interaction parameters are obtained from a Wannier representation of the interlayer-exciton wave functions, and a non-local Rytova-Keldysh model is used to attribute for the dielectric screening of excitons in the two-dimensional material. For sufficiently small exciton concentrations our model predicts the emergence of Mott-insulating states, establishing twisted TMD heterostructures as possible quantum simulators for bosonic many-body systems.

Quantum anomalous Hall effect and electric-field-induced topological phase transition in AB-stacked MoTe${}_2$/WSe${}_2$ moiré heterobilayers

“…The moiré periodicity and the Coulomb repulsion can lead to the localization of an exciton in each moiré unit cell. Such an effect on the exciton condensate can be described by the moiré Bose-Hubbard (BH) Hamiltonian [54,55],…”

Optical non-linearities and translational symmetry breaking in driven-dissipative moiré exciton-polaritons

“…In semiconductor bilayers, moiré materials have unveiled a new class of excitations [12][13][14][15][16]: moiré excitons. Moiré excitons possess properties that make them ideal to explore strongly interacting phases of bosonic matter in uncharted territory, which include prospects for high-temperature and long-lived Bose-Einstein condensates [17,18], the superfluid-Mott transition [19], excitonic insulators [20], and supersolidity [21].…”