Contrasting twisted bilayer graphene and transition metal dichalcogenides for fractional Chern insulators: an emergent gauge picture
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| Format: | Preprint |
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2024
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| _version_ | 1866917709449527296 |
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| author | Li, Heqiu Su, Ying Kim, Yong Baek Kee, Hae-Young Sun, Kai Lin, Shi-Zeng |
| author_facet | Li, Heqiu Su, Ying Kim, Yong Baek Kee, Hae-Young Sun, Kai Lin, Shi-Zeng |
| contents | The recent experimental discovery of the zero-field fractional Chern insulator (FCI) in twisted $\mathrm{MoTe_2}$ moiré superlattices has sparked immense interest in this exotic topological quantum state. The FCI has also been observed in previous experiments in magic angle twisted bilayer graphene (TBG) under a finite magnetic field of about 5 Tesla. Generally, the stabilization of FCI requires fine-tuning the topological band to satisfy certain conditions. It would still be helpful to have an intuitive picture to understand the different behaviors in twisted $\mathrm{MoTe_2}$ and TBG. Here, we compare them through the lens of emergent gauge fields. In TBG, the system can be mapped to two Dirac fermions coupled to emergent gauge fields with opposite signs. In contrast, the twisted $\mathrm{MoTe_2}$ reduces to a hole with parabolic dispersion coupled to an emergent gauge field. This contrasting gauge structure provides a new perspective on the observed difference: the zero-field FCI is stable in $\mathrm{MoTe_2}$ but absent in TBG. Based on this understanding, we will explore potential strategies for stabilizing FCI in both moiré superlattices. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2402_02251 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Contrasting twisted bilayer graphene and transition metal dichalcogenides for fractional Chern insulators: an emergent gauge picture Li, Heqiu Su, Ying Kim, Yong Baek Kee, Hae-Young Sun, Kai Lin, Shi-Zeng Mesoscale and Nanoscale Physics Strongly Correlated Electrons The recent experimental discovery of the zero-field fractional Chern insulator (FCI) in twisted $\mathrm{MoTe_2}$ moiré superlattices has sparked immense interest in this exotic topological quantum state. The FCI has also been observed in previous experiments in magic angle twisted bilayer graphene (TBG) under a finite magnetic field of about 5 Tesla. Generally, the stabilization of FCI requires fine-tuning the topological band to satisfy certain conditions. It would still be helpful to have an intuitive picture to understand the different behaviors in twisted $\mathrm{MoTe_2}$ and TBG. Here, we compare them through the lens of emergent gauge fields. In TBG, the system can be mapped to two Dirac fermions coupled to emergent gauge fields with opposite signs. In contrast, the twisted $\mathrm{MoTe_2}$ reduces to a hole with parabolic dispersion coupled to an emergent gauge field. This contrasting gauge structure provides a new perspective on the observed difference: the zero-field FCI is stable in $\mathrm{MoTe_2}$ but absent in TBG. Based on this understanding, we will explore potential strategies for stabilizing FCI in both moiré superlattices. |
| title | Contrasting twisted bilayer graphene and transition metal dichalcogenides for fractional Chern insulators: an emergent gauge picture |
| topic | Mesoscale and Nanoscale Physics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2402.02251 |