Emergent Interacting Phases in the Strong Coupling Limit of Twisted M-Valley Moir\'e Systems: Application to SnSe${}_2$

TL;DR

This paper models twisted SnSe2 moiré systems, revealing a variety of exotic correlated quantum phases such as spin liquids, valence bond solids, and dimerized states, depending on stacking and interaction regimes.

Contribution

It constructs a detailed interacting Wannier model for twisted SnSe2, uncovering new quantum phases in strong coupling regimes for both AA and AB stacking configurations.

Findings

Identification of dimerized and valence bond solid phases in AA stacking.

Discovery of a classical spin liquid phase in AB stacking.

Demonstration of the system's tunability to realize diverse quantum phases.

Abstract

We construct an interacting Wannier model for both AA-stacked and AB-stacked twisted SnSe2, revealing a rich landscape of correlated quantum phases. For the AA-stacked case, the system is effectively described by a three-orbital triangular lattice model, where each orbital corresponds to a valley and exhibits an approximate one-dimensional hopping structure due to a new momentum-space non-symmorphic symmetry. By exploring the interacting phase diagram using a combination of theoretical methods, including Hartree-Fock mean-field theory and exact solutions of the spin model in certain limits, we identify several exotic quantum phases. These include a dimerized phase with finite residual entropy, valence bond solids, and quantum paramagnetism. In the AB-stacked case, the system realizes an interacting kagome lattice model, where the Wannier orbitals associated with the three valleys form three sublattices. In the strong coupling regime, we use cluster mean-field methods to demonstrate the emergence of a classical spin liquid phase due to the frustrated lattice structure. The high tunability of the moir\'e system, which allows control over both the filling and interaction strength (via twist angle), renders twisted SnSe2 a versatile platform for realizing a wide range of exotic correlated quantum phases.