Graphene-based moire superlattices provide a versatile platform for exploring novel correlated and topological electronic states, driven by enhanced Coulomb interactions within flat bands. The intrinsic tunability of graphene s multiple degrees of freedom enables precise control over these complex quantum phases. In this study, we observe a range of competing phases and their transitions in rhombohedrally stacked hexalayer graphene on hexagonal boron nitride (r-6G/hBN) moire superlattices. When electrons are polarized away from the moire superlattice, we firstly identify a Chern insulator with reversible Chern numbers at v = 1 (one electron per moire cell), attributed to the competition between bulk and edge magnetizations.Then, we detect transitions between three distinct insulating states at v = 2, driven by vertical displacement field D and vertical magnetic field B. These insulating phases are distinguished as spin-antiferromagnetic, spin-polarized, and valley-polarized insulators, based on their responses to parallel and perpendicular magnetic fields. When electrons are polarized toward the moire superlattice, in a device with large twist angle, insulating states appear at v = 1/3 and 2/3 at zero magnetic field, and v = 1/2 in a magnetic field. Our findings reveal a rich interplay of charge, isospin, topology and magnetic field in rhombohedral graphene moire superlattices.
@article{arxiv.2412.09985,
title = {Switchable Chern insulator, isospin competitions and charge density waves in rhombohedral graphene moire superlattices},
author = {Jian Zheng and Size Wu and Kai Liu and Bosai Lyu and Shuhan Liu and Yating Sha and Zhengxian Li and Kenji Watanabe and Takashi Taniguchi and Jinfeng Jia and Zhiwen Shi and Guorui Chen},
journal= {arXiv preprint arXiv:2412.09985},
year = {2024}
}