Magnetic Ground States of Honeycomb Lattice Wigner Crystals

In recent years, moiré materials constructed using two layers of transition metal dichalcogenides have been used to simulate the Hubbard model on triangular lattice procuring strongly correlated physics in half-filled (n=1) flat bands. Lattice Wigner crystal states, at other fractional fillings like n=2/3, 1/2, and 1/3, are also stabilized by long-range Coulomb interactions in these two-dimensional triangular moiré lattices. Recent ab-initio work on the Gamma-valley transition metal dichalcogenide homobilayers unveiled effective moiré honeycomb lattices near the Fermi level. We employ large-scale unrestricted Hartree-Fock techniques to unveil the magnetic phase diagrams of honeycomb lattice Wigner crystals. For the three lattice filling factors with the largest charge gaps, n = 2/3, 1/2, 1/3, the magnetic phase diagrams contain multiple phases, including ones with non-collinear and non-coplanar spin arrangements. We discuss magnetization evolution with the external magnetic field, which has potential as an experimental signature of these exotic spin states. Our theoretical results^[1] could potentially be validated in moiré materials formed from group VI transition metal dichalcogenide twisted homobilayers.

[1] N. Kaushal et.al., arXiv:2206.10024 (2022).