Metal-insulator transition in transition metal dichalcogenide heterobilayer moir\'e superlattices

TL;DR

This study uses exact diagonalization to explore the metal-insulator transition in twisted bilayer transition metal dichalcogenides, revealing phase boundaries and charge gap estimates in moiré superlattices.

Contribution

It provides the first detailed phase diagram and analysis of correlation-driven transitions in narrow moiré bands of transition metal dichalcogenide heterobilayers.

Findings

Identified the phase boundary for metal-insulator transition.

Estimated charge gaps in the insulating phase.

Analyzed the nature of the phase transition.

Abstract

Moir\'e superlattices formed in two-dimensional semiconductor heterobilayers provide a new realization of Hubbard model physics in which the number of electrons per effective atom can be tuned at will. We report on an exact diagonalization study of the electronic properties of half-filled narrow moir\'e bands in which correlation strengths are varied by changing twist angles or interaction strengths. We construct a phase diagram for the bilayer, identifying where the metal-insulator phase transition occurs, estimating the sizes of the charge gaps in the insulating phase, and commenting on the nature of the transition and the importance of sub-dominant interaction parameters.