Time-reversal symmetry breaking fractional quantum spin Hall insulator in moiré MoTe2
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arXiv
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| Autori principali: | , , , , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866929671155744768 |
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| author | Kang, Kaifei Qiu, Yichen Shen, Bowen Lee, Kihong Xia, Zhengchao Zeng, Yihang Watanabe, Kenji Taniguchi, Takashi Shan, Jie Mak, Kin Fai |
| author_facet | Kang, Kaifei Qiu, Yichen Shen, Bowen Lee, Kihong Xia, Zhengchao Zeng, Yihang Watanabe, Kenji Taniguchi, Takashi Shan, Jie Mak, Kin Fai |
| contents | Twisted bilayer transition metal dichalcogenide semiconductors, which support flat Chern bands with enhanced interaction effects, realize a platform for fractional Chern insulators and fractional quantum spin Hall (FQSH) insulators. A recent experiment has reported the emergence of a FQSH insulator protected by spin-Sz conservation at a moiré lattice filling factor ν=3 in 2.1-degree twisted bilayer MoTe2. Theoretical studies have proposed both time-reversal symmetric and asymmetric ground states as possible candidates for the observed FQSH insulator, but the nature of the state remains unexplored. Here we report the observation of spontaneous time-reversal symmetry breaking at generic fillings in 2.1-degree twisted bilayer MoTe2 from ν<1 all the way to ν>6 except at ν=2, 4, and 6. Although zero Hall response is observed at ν=3 for magnetic fields higher than 20 mT, a finite anomalous Hall response accompanied by a magnetic hysteresis is observed at lower magnetic fields, demonstrating spontaneous time-reversal symmetry breaking. Our work shows the tendency towards ferromagnetism by doping the first three pairs of conjugate Chern bands in the material; it also sheds light on the nature of the FQSH insulator at ν=3. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_02525 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Time-reversal symmetry breaking fractional quantum spin Hall insulator in moiré MoTe2 Kang, Kaifei Qiu, Yichen Shen, Bowen Lee, Kihong Xia, Zhengchao Zeng, Yihang Watanabe, Kenji Taniguchi, Takashi Shan, Jie Mak, Kin Fai Mesoscale and Nanoscale Physics Strongly Correlated Electrons Twisted bilayer transition metal dichalcogenide semiconductors, which support flat Chern bands with enhanced interaction effects, realize a platform for fractional Chern insulators and fractional quantum spin Hall (FQSH) insulators. A recent experiment has reported the emergence of a FQSH insulator protected by spin-Sz conservation at a moiré lattice filling factor ν=3 in 2.1-degree twisted bilayer MoTe2. Theoretical studies have proposed both time-reversal symmetric and asymmetric ground states as possible candidates for the observed FQSH insulator, but the nature of the state remains unexplored. Here we report the observation of spontaneous time-reversal symmetry breaking at generic fillings in 2.1-degree twisted bilayer MoTe2 from ν<1 all the way to ν>6 except at ν=2, 4, and 6. Although zero Hall response is observed at ν=3 for magnetic fields higher than 20 mT, a finite anomalous Hall response accompanied by a magnetic hysteresis is observed at lower magnetic fields, demonstrating spontaneous time-reversal symmetry breaking. Our work shows the tendency towards ferromagnetism by doping the first three pairs of conjugate Chern bands in the material; it also sheds light on the nature of the FQSH insulator at ν=3. |
| title | Time-reversal symmetry breaking fractional quantum spin Hall insulator in moiré MoTe2 |
| topic | Mesoscale and Nanoscale Physics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2501.02525 |