Seminar: Strong Inter-valley Electron-Phonon Coupling in Magic-Angle Twisted Bilayer Graphene

陈宇林

牛津大学物理系

报告时间：2023年12月13日（周三）下午14:30

报告地点：紫金港校区段永平教学楼2号楼212报告厅

摘要：

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, using angle-resolved photoemission spectroscopy with micrometer spatial resolution, we discover 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. Crucially, the replicas are evenly spaced in energy, separated by 150 ± 15 meV, signalling 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. 

报告人简介：

陈宇林，牛津大学物理系教授。2000年获中国科学技术大学物理学学士学位，2008年获斯坦福大学物理学博士学位。2008-2011年在美国SLAC加速器国家实验室任博士后、副研究员、研究员。2012年加入牛津大学物理系，历任讲师、副教授、教授。2014年兼任清华大学物理系教授。2015年起任上海科技大学物质学院凝聚态物理与光子科学研究部主任、特聘教授。陈宇林教授的研究兴趣主要是利用角分辨光电子能谱研究新型材料（拓扑量子材料、非常规超导体、低维量子材料等）的电子结构探索工作。共发表论文200余篇，被引次数超过3万次。曾荣获Outstanding Young Researcher Award (Macronix Prize)、William E. and Diane M. Spicer Young Investigator Award等奖项。