Parent Berry curvature and the ideal anomalous Hall crystal

Parent Berry curvature and the ideal anomalous Hall crystal

July 10, 2024 | Tixuan Tan and Trithep Devakul*
The paper investigates the formation of an anomalous Hall crystal (AHC) in a parent band with uniform Berry curvature in the presence of strong repulsive interactions or a periodic electrostatic potential. The authors demonstrate that, at high parent Berry curvature, strong interactions can lead to the spontaneous breaking of continuous translation symmetry, resulting in an AHC with an integer Chern number. This is contrasted with the formation of a Wigner crystal in a trivial parent band under similar conditions. The periodic electrostatic potential, on the other hand, induces a competing state with a Chern number opposite to that of the AHC. The theory is applied to rhombohedral multilayer graphene, where the integer and fractional quantum anomalous Hall effects have been observed. The authors provide a unified perspective on the observed phenomena and offer a recipe for engineering new topological states. The study uses a model Hamiltonian to isolate the effects of parent Berry curvature and demonstrates that the AHC can be mapped to a Wigner crystal through unitary transformations. The results are validated through numerical simulations and analytic wavefunction ansatz, showing good agreement. The findings highlight the interplay between electronic interactions and topological properties in the context of parent bands.The paper investigates the formation of an anomalous Hall crystal (AHC) in a parent band with uniform Berry curvature in the presence of strong repulsive interactions or a periodic electrostatic potential. The authors demonstrate that, at high parent Berry curvature, strong interactions can lead to the spontaneous breaking of continuous translation symmetry, resulting in an AHC with an integer Chern number. This is contrasted with the formation of a Wigner crystal in a trivial parent band under similar conditions. The periodic electrostatic potential, on the other hand, induces a competing state with a Chern number opposite to that of the AHC. The theory is applied to rhombohedral multilayer graphene, where the integer and fractional quantum anomalous Hall effects have been observed. The authors provide a unified perspective on the observed phenomena and offer a recipe for engineering new topological states. The study uses a model Hamiltonian to isolate the effects of parent Berry curvature and demonstrates that the AHC can be mapped to a Wigner crystal through unitary transformations. The results are validated through numerical simulations and analytic wavefunction ansatz, showing good agreement. The findings highlight the interplay between electronic interactions and topological properties in the context of parent bands.
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