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arXiv · 2202.12330

Spectroscopy Signatures of Electron Correlations in a Trilayer Graphene/hBN Moir\'e Superlattice

Jixiang Yang·Guorui Chen·Tianyi Han·Qihang Zhang·Ya-Hui Zhang·Lili Jiang·Bosai Lyu·Hongyuan Li·Kenji Watanabe·Takashi Taniguchi·Zhiwen Shi·Todadri Senthil·Yuanbo Zhang·Feng Wang·Long Ju
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Abstract

ABC-stacked trilayer graphene/hBN moir\'e superlattice (TLG/hBN) has emerged as a playground for correlated electron physics. We report spectroscopy measurements of dual-gated TLG/hBN using Fourier transformed infrared photocurrent spectroscopy. We observed a strong optical transition between moir\'e mini-bands that narrows continuously as a bandgap is opened by gating, indicating a reduction of the single particle bandwidth. At half-filling of the valence flat band, a broad absorption peak emerges at ~18 meV, indicating direct optical excitation across an emerging Mott gap. Similar photocurrent spectra are observed in two other correlated insulating states at quarter- and half-filling of the first conduction band. Our findings provide key parameters of the Hubbard model for the understanding of electron correlation in TLG/hBN.

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Jixiang Yang, Guorui Chen, Tianyi Han, Qihang Zhang, Ya-Hui Zhang, Lili Jiang, Bosai Lyu, Hongyuan Li, Kenji Watanabe, Takashi Taniguchi, Zhiwen Shi, Todadri Senthil, Yuanbo Zhang, Feng Wang, Long Ju. 2022-02-24. Spectroscopy Signatures of Electron Correlations in a Trilayer Graphene/hBN Moir\'e Superlattice. https://doi.org/10.1126/science.abg3036

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