Fractional and Symmetry-Broken Chern Insulators in Tunable Moiré Superlattices.

Cheng, Bin; Pan, Cheng; Che, Shi; Wang, Peng; Wu, Yong; Watanabe, Kenji; Taniguchi, Takashi; Ge, Supeng et al. · Nano Lett · 2019

basic_science · Level V

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Abstract

We study dual-gated graphene bilayer/hBN moiré superlattices. Under zero magnetic field, we observe additional resistance peaks as the charge density varies. The peaks' resistivities vary approximately quadratically with an applied perpendicular displacement field <i>D</i>. Data fit to a continuum model yield a bilayer/hBN interaction energy scale ∼30 ± 10 meV. Under a perpendicular magnetic field, we observe Hofstadter butterfly spectra as well as symmetry-broken and fractional Chern insulator states. Their topology and lattice symmetry breaking is <i>D</i>-tunable, enabling the realization of new topological states in this system.