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arXiv · 2310.05667

Interplay of valley, layer and band topology towards interacting quantum phases in moir\'e bilayer graphene

Yungi Jeong·Hangyeol Park·Taeho Kim·Kenji Watanabe·Takashi Taniguchi·Jeil Jung·Joonho Jang
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Abstract

In Bernal-stacked bilayer graphene (BBG), the Landau levels give rise to an intimate connection between valley and layer degrees of freedom. Adding a moir\'e superlattice potential enriches the BBG physics with the formation of topological minibands - potentially leading to tunable exotic quantum transport. Here, we present magnetotransport measurements of a high-quality bilayer graphene-hexagonal boron nitride (hBN) heterostructure. The zero-degree alignment generates a strong moir\'e superlattice potential for the electrons in BBG and the resulting Landau fan diagram of longitudinal and Hall resistance displays a Hofstadter butterfly pattern with a high level of detail. We demonstrate that the intricate relationship between valley and layer degrees of freedom controls the topology of moir\'e-induced bands, significantly influencing the energetics of interacting quantum phases in the BBG superlattice. We further observe signatures of field-induced correlated insulators, helical edge states and clear quantizations of interaction-driven topological quantum phases, such as symmetry broken Chern insulators.

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Yungi Jeong, Hangyeol Park, Taeho Kim, Kenji Watanabe, Takashi Taniguchi, Jeil Jung, Joonho Jang. 2023-10-09. Interplay of valley, layer and band topology towards interacting quantum phases in moir\'e bilayer graphene. https://doi.org/10.1038/s41467-024-50475-x

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