Interplay between topology and electron-electron interactions in the moir\'{e} MoTe$_{\mathrm{2}}$/WSe$_{\mathrm{2}}$ heterobilayer

TL;DR

This paper investigates how topology and electron-electron interactions influence the electronic phases in a moiré MoTe2/WSe2 heterobilayer, revealing phase transitions driven by electric fields and Coulomb interactions.

Contribution

It introduces an effective two-band model with complex hoppings and Coulomb interactions to analyze topological and magnetic phases in the heterobilayer.

Findings

Transition from antiferromagnetic insulator to topological insulator with electric field

Emergence of a trivial magnetic metallic phase at higher fields

Influence of Coulomb interactions on topological and charge density wave states

Abstract

We study, the interplay between topology and electron-electron interactions in the moir\'{e} MoTe\(_2\)/WSe\(_2\) heterobilayer. In our analysis we apply an effective two-band model with complex hoppings that incorporates the Ising-type spin-orbit coupling and lead to a non-trivial topology after the application of perpendicular electric field (displacement field). The model is supplemented by on-site and inter-site Coulomb repulsion terms and treated by both Hartree-Fock and Gutzwiller methods. According to our analysis, for the case of one hole per moir\'{e} unit cell, the system undergoes two phase transitions with increasing displacement field. The first one is from an in-plane 120$^\circ$ antiferromagnetic charge transfer insulator to a topological insulator. At the second transition, the system becomes topologically trivial and an out-of-plane ferrimagnetic metallic phase becomes stable. In the topological region a spontaneous spin-polarization appears and the holes are distributed in both layers. Additionally, we analyze the influence of the intersite Coulomb repulsion terms on the appearance of the topological phase as well as on the formation of the charge density wave state. We discuss the obtained results in the context of available experimental data.