Emergent Symmetry and Valley Chern Insulator in Twisted Double-Bilayer Graphene
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| Format: | Preprint |
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2020
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| author | Wang, Yimeng Burg, G. William Lian, Biao Watanabe, Kenji Taniguchi, Takashi Bernevig, B. Andrei Tutuc, Emanuel |
| author_facet | Wang, Yimeng Burg, G. William Lian, Biao Watanabe, Kenji Taniguchi, Takashi Bernevig, B. Andrei Tutuc, Emanuel |
| contents | Theoretical calculations show that twisted double bilayer graphene (TDBG) under a transverse electric field develops a valley Chern number 2 at charge neutrality. Using thermodynamic and thermal activation measurements we report the experimental observation of a universal closing of the charge neutrality gap in the Hofstadter spectrum of TDBG at 1/2 magnetic flux per unit cell, in agreement with theoretical predictions for a valley Chern number 2 gap. Our theoretical analysis of the experimental data shows that the interaction energy, while larger than the flat-band bandwidth in TDBG near 1°does not alter the emergent valley symmetry or the single-particle band topology. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2006_14000 |
| institution | arXiv |
| publishDate | 2020 |
| record_format | arxiv |
| spellingShingle | Emergent Symmetry and Valley Chern Insulator in Twisted Double-Bilayer Graphene Wang, Yimeng Burg, G. William Lian, Biao Watanabe, Kenji Taniguchi, Takashi Bernevig, B. Andrei Tutuc, Emanuel Mesoscale and Nanoscale Physics Strongly Correlated Electrons Theoretical calculations show that twisted double bilayer graphene (TDBG) under a transverse electric field develops a valley Chern number 2 at charge neutrality. Using thermodynamic and thermal activation measurements we report the experimental observation of a universal closing of the charge neutrality gap in the Hofstadter spectrum of TDBG at 1/2 magnetic flux per unit cell, in agreement with theoretical predictions for a valley Chern number 2 gap. Our theoretical analysis of the experimental data shows that the interaction energy, while larger than the flat-band bandwidth in TDBG near 1°does not alter the emergent valley symmetry or the single-particle band topology. |
| title | Emergent Symmetry and Valley Chern Insulator in Twisted Double-Bilayer Graphene |
| topic | Mesoscale and Nanoscale Physics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2006.14000 |