Anomalous Hall Crystals in Graphene: interaction-driven Chern bands at zero magnetic field

Recent experiments have discovered that pentalayer-graphene subject to a moire superlattice spontaneously breaks time-reversal, resulting in a quantized anomalous Hall effect at zero magnetic field. At fractional filling, the material exhibits a zero-field fractional quantum Hall effect. In contrast to other moire-materials, the origin of Chern bands in this material is not so clear. I will present a theoretical picture in which Chern bands arise from an “anomalous Hall crystal” stabilized primarily by interactions. So far this picture is supported primarily by mean-field calculations, so I’ll conclude with some open questions about how the AHC could be verified.

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