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DOE OSTI · 2499452

Strong electron–phonon coupling in magic-angle twisted bilayer graphene

Chen, Cheng [ShanghaiTech University (China); University of Oxford (United Kingdom)]·Nuckolls, Kevin P. [Massachusetts Institute of Technology (MIT), Cambridge, MA (United States); Princeton University, NJ (United States)] (ORCID:0000000210787113)·Ding, Shuhan [Emory University, Atlanta, GA (United States)]·Miao, Wangqian [University of California, Santa Barbara, CA (United States)]·Wong, Dillon [Princeton University, NJ (United States)]·Oh, Myungchul [Pohang University of Science and Technology (POSTECH) (Korea, Republic of); Princeton University, NJ (United States)] (ORCID:0000000304771390)·Lee, Ryan L. [Princeton University, NJ (United States)]·He, Shanmei [University of Oxford (United Kingdom)]·Peng, Cheng [University of Oxford (United Kingdom)] (ORCID:0009000634331467)·Pei, Ding [ShanghaiTech University (China)]·Li, Yiwei [Wuhan University (China)]·Hao, Chenyue [Beijing Normal University (China)]·Yan, Haoran [Emory University, Atlanta, GA (United States)]·Xiao, Hanbo [ShanghaiTech University (China)] (ORCID:0000000182473378)·Gao, Han [ShanghaiTech University (China)]·Li, Qiao [ShanghaiTech University (China)]·Zhang, Shihao [ShanghaiTech University (China)] (ORCID:0000000257875022)·Liu, Jianpeng [ShanghaiTech University (China)] (ORCID:0000000285640415)·He, Lin [Beijing Normal University (China)] (ORCID:0000000152511687)·Watanabe, Kenji [National Institute for Materials Science, Tsukuba (Japan)] (ORCID:0000000337018119)·Taniguchi, Takashi [National Institute for Materials Science, Tsukuba (Japan)] (ORCID:0000000214673105)·Jozwiak, Chris [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000209803753)·Bostwick, Aaron [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000290082980)·Rotenberg, Eli [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000239798844)·Li, Chu [Hong Kong University of Science and Technology (China)] (ORCID:0000000324412205)·Han, Xu [Hong Kong University of Science and Technology (China)] (ORCID:0000000161163258)·Pan, Ding [Hong Kong University of Science and Technology (China)] (ORCID:0000000223530130)·Liu, Zhongkai [ShanghaiTech University (China)] (ORCID:0000000333738039)·Dai, Xi [Hong Kong University of Science and Technology (China)] (ORCID:0000000223960966)·Liu, Chaoxing [Pennsylvania State University, University Park, PA (United States)] (ORCID:0000000318811365)·Bernevig, B. Andrei [Princeton University, NJ (United States); Donostia International Physics Center (Spain); IKERBASQUE, Basque Foundation for Science, Bilbao (Spain)] (ORCID:0000000163374024)·Wang, Yao [Emory University, Atlanta, GA (United States); Clemson University, SC (United States)] (ORCID:0000000317360187)·Yazdani, Ali [Princeton University, NJ (United States)] (ORCID:0000000349968904)·Chen, Yulin [ShanghaiTech University (China); University of Oxford (United Kingdom)] (ORCID:0000000189609725)
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Abstract

The unusual properties of superconductivity in magic-angle twisted bilayer graphene (MATBG) have sparked considerable 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, by utilizing angle-resolved photoemission spectroscopy with micrometre spatial resolution, we reveal flat-band replicas in superconducting MATBG, where MATBG is unaligned with its hexagonal boron nitride substrate. These replicas show 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 hexagonal boron nitride 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 intervalley scattering. These findings, although they do not necessarily put electron–phonon coupling as the main driving force for the superconductivity in MATBG, unravel the electronic structure inherent in superconducting MATBG, thereby providing crucial information for understanding the unusual electronic landscape from which its superconductivity is derived.

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75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITYElectronic properties and devicesElectronic properties and materialsSuperconducting properties and materialselectronic properties and deviceselectronic properties and materialssuperconducting properties and materials

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Chen, Cheng [ShanghaiTech University (China); University of Oxford (United Kingdom)], Nuckolls, Kevin P. [Massachusetts Institute of Technology (MIT), Cambridge, MA (United States); Princeton University, NJ (United States)] (ORCID:0000000210787113), Ding, Shuhan [Emory University, Atlanta, GA (United States)], Miao, Wangqian [University of California, Santa Barbara, CA (United States)], Wong, Dillon [Princeton University, NJ (United States)], Oh, Myungchul [Pohang University of Science and Technology (POSTECH) (Korea, Republic of); Princeton University, NJ (United States)] (ORCID:0000000304771390), Lee, Ryan L. [Princeton University, NJ (United States)], He, Shanmei [University of Oxford (United Kingdom)], Peng, Cheng [University of Oxford (United Kingdom)] (ORCID:0009000634331467), Pei, Ding [ShanghaiTech University (China)], Li, Yiwei [Wuhan University (China)], Hao, Chenyue [Beijing Normal University (China)], Yan, Haoran [Emory University, Atlanta, GA (United States)], Xiao, Hanbo [ShanghaiTech University (China)] (ORCID:0000000182473378), Gao, Han [ShanghaiTech University (China)], Li, Qiao [ShanghaiTech University (China)], Zhang, Shihao [ShanghaiTech University (China)] (ORCID:0000000257875022), Liu, Jianpeng [ShanghaiTech University (China)] (ORCID:0000000285640415), He, Lin [Beijing Normal University (China)] (ORCID:0000000152511687), Watanabe, Kenji [National Institute for Materials Science, Tsukuba (Japan)] (ORCID:0000000337018119), Taniguchi, Takashi [National Institute for Materials Science, Tsukuba (Japan)] (ORCID:0000000214673105), Jozwiak, Chris [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000209803753), Bostwick, Aaron [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000290082980), Rotenberg, Eli [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000239798844), Li, Chu [Hong Kong University of Science and Technology (China)] (ORCID:0000000324412205), Han, Xu [Hong Kong University of Science and Technology (China)] (ORCID:0000000161163258), Pan, Ding [Hong Kong University of Science and Technology (China)] (ORCID:0000000223530130), Liu, Zhongkai [ShanghaiTech University (China)] (ORCID:0000000333738039), Dai, Xi [Hong Kong University of Science and Technology (China)] (ORCID:0000000223960966), Liu, Chaoxing [Pennsylvania State University, University Park, PA (United States)] (ORCID:0000000318811365), Bernevig, B. Andrei [Princeton University, NJ (United States); Donostia International Physics Center (Spain); IKERBASQUE, Basque Foundation for Science, Bilbao (Spain)] (ORCID:0000000163374024), Wang, Yao [Emory University, Atlanta, GA (United States); Clemson University, SC (United States)] (ORCID:0000000317360187), Yazdani, Ali [Princeton University, NJ (United States)] (ORCID:0000000349968904), Chen, Yulin [ShanghaiTech University (China); University of Oxford (United Kingdom)] (ORCID:0000000189609725). 2024-12-11. Strong electron–phonon coupling in magic-angle twisted bilayer graphene. https://doi.org/10.1038/s41586-024-08227-w

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