Unconventional Orbital Magnetism in Graphene-based Fractional Chern Insulators
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arXiv
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| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Xie, Jian Zhang, Zaizhe Chen, Xi Kwan, Yves H. Huo, Zihao Herzog-Arbeitman, Jonah Guo, Liangliang Watanabe, Kenji Taniguchi, Takashi Liu, Kaihui Xie, X. C. Bernevig, B. Andrei Song, Zhi-Da Lu, Xiaobo |
| author_facet | Xie, Jian Zhang, Zaizhe Chen, Xi Kwan, Yves H. Huo, Zihao Herzog-Arbeitman, Jonah Guo, Liangliang Watanabe, Kenji Taniguchi, Takashi Liu, Kaihui Xie, X. C. Bernevig, B. Andrei Song, Zhi-Da Lu, Xiaobo |
| contents | Orbital magnetism in graphene originates from correlation-driven spontaneous valley symmetry breaking1-7. It can lead to various anomalous transport phenomena such as integer and fractional quantum anomalous Hall effects8-11. In general, the in-plane magnetic field B|| primarily couples to the spin degrees of freedom in graphene and has long been presumed to have a negligible effect on orbital magnetism due to the ultra-weak spin-orbit coupling12-18. In this work, we report multiple unconventional orbital magnetic phenomena that are highly sensitive to the B|| field in graphene/hBN superlattices hosting both integer and fractional Chern insulators (FCIs). We observed chirality-switching behaviors of the Chern insulator at moiré filling factor ν = 1 under a finite B_par, demonstrating that both the C = +-1 states are permissible ground states at zero perpendicular magnetic field B_per. For the FCI at ν = 2/3, we observed topological phase transitions between two states characterized by Hall resistivity \r{ho}xy = +-3h/2e2 under both B_per and B_par fields. In-plane B|| field can effectively suppress the FCI state at zero B_per field and enhance the FCI state with the opposite chirality, as resolved in Landau fan diagrams. Moreover, we observed rich phase transitions at 1 < ν < 2, accompanied by intervalley coherence and anomalous Hall effects (AHE) that can be triggered by sweeping either B_per or B_par. Our work has unveiled new properties of orbital magnetism, providing a new knob for engineering various AHE in graphene. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_01485 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Unconventional Orbital Magnetism in Graphene-based Fractional Chern Insulators Xie, Jian Zhang, Zaizhe Chen, Xi Kwan, Yves H. Huo, Zihao Herzog-Arbeitman, Jonah Guo, Liangliang Watanabe, Kenji Taniguchi, Takashi Liu, Kaihui Xie, X. C. Bernevig, B. Andrei Song, Zhi-Da Lu, Xiaobo Mesoscale and Nanoscale Physics Strongly Correlated Electrons Orbital magnetism in graphene originates from correlation-driven spontaneous valley symmetry breaking1-7. It can lead to various anomalous transport phenomena such as integer and fractional quantum anomalous Hall effects8-11. In general, the in-plane magnetic field B|| primarily couples to the spin degrees of freedom in graphene and has long been presumed to have a negligible effect on orbital magnetism due to the ultra-weak spin-orbit coupling12-18. In this work, we report multiple unconventional orbital magnetic phenomena that are highly sensitive to the B|| field in graphene/hBN superlattices hosting both integer and fractional Chern insulators (FCIs). We observed chirality-switching behaviors of the Chern insulator at moiré filling factor ν = 1 under a finite B_par, demonstrating that both the C = +-1 states are permissible ground states at zero perpendicular magnetic field B_per. For the FCI at ν = 2/3, we observed topological phase transitions between two states characterized by Hall resistivity \r{ho}xy = +-3h/2e2 under both B_per and B_par fields. In-plane B|| field can effectively suppress the FCI state at zero B_per field and enhance the FCI state with the opposite chirality, as resolved in Landau fan diagrams. Moreover, we observed rich phase transitions at 1 < ν < 2, accompanied by intervalley coherence and anomalous Hall effects (AHE) that can be triggered by sweeping either B_per or B_par. Our work has unveiled new properties of orbital magnetism, providing a new knob for engineering various AHE in graphene. |
| title | Unconventional Orbital Magnetism in Graphene-based Fractional Chern Insulators |
| topic | Mesoscale and Nanoscale Physics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2506.01485 |