Does Moire Matter? Critical Moire Dependence with Quantum Fluctuations in Graphene Based Integer and Fractional Chern Insulators

Zihao Huo; Wenxuan Wang; Jian Xie; Yves H. Kwan; Jonah Herzog-Arbeitman; Zaizhe Zhang; Qiu Yang; Min Wu; Kenji Watanabe; Takashi Taniguchi; Kaihui Liu; Nicolas Regnault; B. Andrei Bernevig; Xiaobo Lu

arXiv · 2510.15309

Does Moire Matter? Critical Moire Dependence with Quantum Fluctuations in Graphene Based Integer and Fractional Chern Insulators

Zihao Huo·Wenxuan Wang·Jian Xie·Yves H. Kwan·Jonah Herzog-Arbeitman·Zaizhe Zhang·Qiu Yang·Min Wu·Kenji Watanabe·Takashi Taniguchi·Kaihui Liu·Nicolas Regnault·B. Andrei Bernevig·Xiaobo Lu

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Abstract

Rhombohedral multilayer graphene has emerged as a powerful platform for investigating flat-band-driven correlated phenomena, yet most aspects remain not understood. In this work, we systematically study the moire-dependent band topology in rhombohedral hexalayer graphene. For the first time we demonstrate that the moire twist angle plays a crucial role in the formation of the moire Chern insulators in rhombohedral hexalayer graphene/hexagonal boron nitride (RHG/hBN) moire superlattices. In the moire-distant regime at filling factor v = 1, only systems with a twist angle {\theta} < 1.1{\deg} exhibit an integer moire Chern insulator, while the fractional Chern insulator at v = 2/3 requires smaller twist angle to be stabilized. Our theoretical modelling, which includes quantum fluctuations and exact diagonalization results, suggests that mean-field theory, which has been widely adopted, does not explain the twist-angle dependence of the v = 1 phase diagram, and that correlation effects are crucial. Moreover, we realize two distinct stacking configurations ( /Xi=0 and /Xi=1) between graphene and hBN, and find that both cases can yield a Chern insulator at v = 1. Our experimental work upends the current mean-field paradigm, illuminates how quantum fluctuations and moir\'e effects shape the RHG/hBN phase diagram, and paves the way for future understanding and engineering of topological correlated states in rhombohedral graphene moire systems.

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Zihao Huo, Wenxuan Wang, Jian Xie, Yves H. Kwan, Jonah Herzog-Arbeitman, Zaizhe Zhang, Qiu Yang, Min Wu, Kenji Watanabe, Takashi Taniguchi, Kaihui Liu, Nicolas Regnault, B. Andrei Bernevig, Xiaobo Lu. 2025-10-17. Does Moire Matter? Critical Moire Dependence with Quantum Fluctuations in Graphene Based Integer and Fractional Chern Insulators. https://arxiv.org/abs/2510.15309

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