Spectroscopy signatures of electron correlations in a trilayer graphene/hBN moiré superlattice

• Main Authors: Yang, Jixiang (Author), Chen, Guorui (Author), Han, Tianyi (Author), Zhang, Qihang (Author), Zhang, Ya-Hui (Author), Jiang, Lili (Author), Lyu, Bosai (Author), Li, Hongyuan (Author), Watanabe, Kenji (Author), Taniguchi, Takashi (Author), Shi, Zhiwen (Author), Senthil, Todadri (Author), Zhang, Yuanbo (Author), Wang, Feng (Author), Ju, Long (Author)
• Format: Article
• Language: English
• Published: American Association for the Advancement of Science (AAAS), 2022-04-20T12:27:23Z.
• Subjects: Article
• Online Access: Get fulltext

<jats:p>ABC-stacked trilayer graphene/hexagonal boron nitride moiré superlattice (TLG/hBN) has emerged as a playground for correlated electron physics. We report spectroscopy measurements of dual-gated TLG/hBN using Fourier transform infrared photocurrent spectroscopy. We observed a strong optical transition between moiré minibands 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 milli-electron volts, 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.</jats:p>