TMDs as a platform for spin liquid physics: A strong coupling study of twisted bilayer WSe$_2$

TL;DR

This paper investigates the potential for quantum spin liquid states in twisted bilayer WSe$_2$ using a strong coupling approach, revealing possible QSL phases near SU(2) symmetry and magnetic order with DM interactions.

Contribution

It introduces a strong coupling model including J1, J2, and DM interactions to explore spin liquid physics in twisted bilayer WSe$_2$, highlighting conditions for QSL emergence.

Findings

Evidence for quantum spin liquid states near SU(2) symmetry.

Long-range magnetic order with DM interactions and anisotropy.

Phase diagram mapping as a function of displacement field.

Abstract

The advent of twisted moir\'e heterostructures as a playground for strongly correlated electron physics has led to a plethora of experimental and theoretical efforts seeking to unravel the nature of the emergent superconducting and insulating states. Amongst these layered compositions of two dimensional materials, transition metal dichalcogenides (TMDs) are by now appreciated as highly-tunable platforms to simulate reinforced electronic interactions in the presence of low-energy bands with almost negligible bandwidth. Here, we focus on the twisted homobilayer WSe$_2$ and the insulating phase at half-filling of the flat bands reported therein. More specifically, we explore the possibility of realizing quantum spin liquid (QSL) physics on the basis of a strong coupling description, including up to second nearest neighbor Heisenberg couplings $J_1$ and $J_2$, as well as Dzyaloshinskii-Moriya (DM) interactions. Mapping out the global phase diagram as a function of an out-of-plane displacement field, we indeed find evidence for putative QSL states, albeit only close to SU$(2)$ symmetric points. In the presence of finite DM couplings and XXZ anisotropy, long-range order is predominantly present, with a mix of both commensurate and incommensurate magnetic phases.