91̽»¨

When two 1T-SnSeâ‚‚ monolayers are stacked with a relative twist, they form a new class of M-point moiré materials—distinct from the well-studied K-point systems exemplified by twisted bilayer graphene. These heterostructures host three time-reversal-symmetric valleys related by threefold rotational symmetry and exhibit emergent momentum-space non-symmorphic symmetries, giving rise to quasi-one-dimensional electron hopping [1]. By combining first-principles calculations with exact solutions of the resulting interacting Wannier models for both AA and AB stacking configurations, we show that twisted SnSeâ‚‚ constitutes a highly tunable platform for correlated quantum phases [2]. In the AA-stacked configuration, the system maps onto a three-orbital triangular model 91̽»¨ing exact spin-dimer states, valence-bond solids, quantum-paramagnetic phases, and Luttinger-liquid behavior, whereas the AB stacking configuration realizes a Kagome Ising model. The interplay between flat electronic bands, nontrivial crystalline symmetries, and tunable interactions establishes M-point moiré systems as versatile simulators of exotic many-body phenomena in two dimensions.

[1] D. Călugăru, Y. Jiang, H. Hu, H. Pi et al., Nature 643, 376–381 (2025).
[2] M. Li, …, H. Hu, arXiv:2508.10098 (2025).