Quantum Phase Diagram of a Moir\'e-Hubbard Model
Abstract
We theoretically study a generalized Hubbard model on moir\'e superlattices of twisted bilayers, and find very rich filling-factor-dependent quantum phase diagrams tuned by interaction strength and twist angle. Strong long-range Coulomb interaction in the moir\'e-Hubbard model induces Wigner crystals at a series of fractional filling factors. The effective lattice of the Wigner crystal is controlled by the filling factor, and can be triangle, rectangle, honeycomb, kagome, etc, providing a single platform to realize many different spin models on various lattices by simply tuning carrier density. In addition to Wigner crystals that are topologically trivial, interaction-induced Chern insulators emerge in the phase diagram. This finding paves a way for engineering interaction-induced quantum anomalous Hall effect in moir\'e-Hubbard systems where the corresponding single-particle moir\'e band is topologically trivial.
Cite
@article{arxiv.2008.08998,
title = {Quantum Phase Diagram of a Moir\'e-Hubbard Model},
author = {Haining Pan and Fengcheng Wu and Sankar Das Sarma},
journal= {arXiv preprint arXiv:2008.08998},
year = {2020}
}
Comments
5 + 7 pages, 6 + 12 figures