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arXiv · 2008.08998

Quantum Phase Diagram of a Moiré-Hubbard Model

Haining Pan·Fengcheng Wu·Sankar Das Sarma
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Abstract

We theoretically study a generalized Hubbard model on moiré 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 moiré-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 moiré-Hubbard systems where the corresponding single-particle moiré band is topologically trivial.

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Haining Pan, Fengcheng Wu, Sankar Das Sarma. 2020-11-06. Quantum Phase Diagram of a Moiré-Hubbard Model. https://doi.org/10.1103/physrevb.102.201104

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