Time: 10:00-11:30, April 2nd (Wednesday, Beijing Time), 2025

时间：2025年4月2日（星期三）10:00-11:30

Host: Prof. Ruihua HE, PI of School of Science, Westlake University

主持人: 西湖大学物理系PI 何睿华

Venue: E10-215, Yungu Campus, Westlake University

地点: 云谷校区E10-215教室

Lecture Language: English

讲座语言: 英文

陈宇林教授

上海科技大学

Prof. Yulin Chen

ShanghaiTech University

主讲人/Speaker:

Yulin received his B.S. from the University of Science & Technology of China in 2000 and Ph.D. in Physics from Stanford University in 2008. After working at SLAC National Accelerator Laboratory briefly, he joined the University of Oxford since 2012 as a Fellow of the Jesus College and university lecturer/associate professor/professor till now. Yulin is also an adjunct professor in Tsinghua University during 2014~2023 and ShanghaiTech University since 2014. Yulin’s research interest lies in understanding the behavior of electrons in unconventional materials, including topological quantum materials, strongly correlated electron systems and functional materials. Yulin is also devoted in developing advanced instrumentation with new capability to drive the current research frontier. Due to his contribution to the field of topological quantum materials, he was awarded the William E. and Diane M. Spicer Young Investigator Award (2009), OCPA Outstanding Young Research Award (2012)，the Nakamura Lecture Award (2017) and Kai Siegbahn Prize (2021). He is also a Highly Cited Researcher listed by the Web of Science.

摘要/Abstract:

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. In this talk, using angle-resolved photoemission spectroscopy with micrometer spatial resolution, we show our observation on the replicas of the flat bands in superconducting MATBG unaligned with its hexagonal boron nitride (hBN) substrate, which are absent in non-superconducting MATBG aligned with the hBN substrate. Remarkably, the replicas are evenly spaced in energy, separated by 150 ± 15 meV, signaling the strong coupling of electrons in MATBG to a bosonic mode of this energy. By comparing our observations to simulations, the formation of replicas is attributed to the presence of strong inter-valley electron-phonon coupling to a K-point phonon mode. In total, the observation of these replica flat bands and the corresponding phonon mode in MATBG could provide important information for understanding the origin and the unusual properties of its superconducting phase.

讲座联系人/Contact:

School of Science, Zeyuan LI, Email: lizeyuan@westlake.edu.cn