Strong Inter-valley Electron-Phonon Coupling in Magic-Angle Twisted Bilayer Graphene
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arXiv
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866910740976238592 |
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| author | Chen, Cheng Nuckolls, Kevin P. Ding, Shuhan Miao, Wangqian Wong, Dillon Oh, Myungchul Lee, Ryan L. He, Shanmei Peng, Cheng Pei, Ding Li, Yiwei Hao, Chenyue Yan, Haoran Xiao, Hanbo Gao, Han Li, Qiao Zhang, Shihao Liu, Jianpeng He, Lin Watanabe, Kenji Taniguchi, Takashi Jozwiak, Chris Bostwick, Aaron Rotenberg, Eli Li, Chu Han, Xu Pan, Ding Liu, Zhongkai Dai, Xi Liu, Chaoxing Bernevig, B. Andrei Wang, Yao Yazdani, Ali Chen, Yulin |
| author_facet | Chen, Cheng Nuckolls, Kevin P. Ding, Shuhan Miao, Wangqian Wong, Dillon Oh, Myungchul Lee, Ryan L. He, Shanmei Peng, Cheng Pei, Ding Li, Yiwei Hao, Chenyue Yan, Haoran Xiao, Hanbo Gao, Han Li, Qiao Zhang, Shihao Liu, Jianpeng He, Lin Watanabe, Kenji Taniguchi, Takashi Jozwiak, Chris Bostwick, Aaron Rotenberg, Eli Li, Chu Han, Xu Pan, Ding Liu, Zhongkai Dai, Xi Liu, Chaoxing Bernevig, B. Andrei Wang, Yao Yazdani, Ali Chen, Yulin |
| contents | The unusual properties of superconductivity in magic-angle twisted bilayer graphene (MATBG) have sparked enormous research interest. However, despite the dedication of intensive experimental efforts and the proposal of several possible pairing mechanisms, the origin of its superconductivity remains elusive. Here, utilizing angle-resolved photoemission spectroscopy with micrometer spatial resolution, we have revealed flat band replicas in superconducting MATBG, where MATBG is unaligned with its hexagonal boron nitride (hBN) substrate11. These replicas exhibit uniform energy spacing, approximately 150 +- 15 meV apart, indicative of strong electron-boson coupling. Strikingly, these replicas are absent in non-superconducting twisted bilayer graphene (TBG) systems, either when MATBG is aligned to hBN or when TBG deviates from the magic angle. Calculations suggest that the formation of these flat band replicas in superconducting MATBG are attributed to the strong coupling between flat band electrons and an optical phonon mode at the graphene K point, facilitated by inter-valley scattering. These findings, although do not necessarily put electron phonon coupling as the main driving force for the superconductivity in MATBG, unravel the unique electronic structure inherent in superconducting MATBG, thereby providing crucial information for understanding the unusual electronic landscape from which the superconductivity is derived. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2303_14903 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Strong Inter-valley Electron-Phonon Coupling in Magic-Angle Twisted Bilayer Graphene Chen, Cheng Nuckolls, Kevin P. Ding, Shuhan Miao, Wangqian Wong, Dillon Oh, Myungchul Lee, Ryan L. He, Shanmei Peng, Cheng Pei, Ding Li, Yiwei Hao, Chenyue Yan, Haoran Xiao, Hanbo Gao, Han Li, Qiao Zhang, Shihao Liu, Jianpeng He, Lin Watanabe, Kenji Taniguchi, Takashi Jozwiak, Chris Bostwick, Aaron Rotenberg, Eli Li, Chu Han, Xu Pan, Ding Liu, Zhongkai Dai, Xi Liu, Chaoxing Bernevig, B. Andrei Wang, Yao Yazdani, Ali Chen, Yulin Mesoscale and Nanoscale Physics Strongly Correlated Electrons The unusual properties of superconductivity in magic-angle twisted bilayer graphene (MATBG) have sparked enormous research interest. However, despite the dedication of intensive experimental efforts and the proposal of several possible pairing mechanisms, the origin of its superconductivity remains elusive. Here, utilizing angle-resolved photoemission spectroscopy with micrometer spatial resolution, we have revealed flat band replicas in superconducting MATBG, where MATBG is unaligned with its hexagonal boron nitride (hBN) substrate11. These replicas exhibit uniform energy spacing, approximately 150 +- 15 meV apart, indicative of strong electron-boson coupling. Strikingly, these replicas are absent in non-superconducting twisted bilayer graphene (TBG) systems, either when MATBG is aligned to hBN or when TBG deviates from the magic angle. Calculations suggest that the formation of these flat band replicas in superconducting MATBG are attributed to the strong coupling between flat band electrons and an optical phonon mode at the graphene K point, facilitated by inter-valley scattering. These findings, although do not necessarily put electron phonon coupling as the main driving force for the superconductivity in MATBG, unravel the unique electronic structure inherent in superconducting MATBG, thereby providing crucial information for understanding the unusual electronic landscape from which the superconductivity is derived. |
| title | Strong Inter-valley Electron-Phonon Coupling in Magic-Angle Twisted Bilayer Graphene |
| topic | Mesoscale and Nanoscale Physics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2303.14903 |