• 文献标题:   Twist-Induced New Phonon Scattering Pathways in Bilayer Graphene Probed by Helicity-Resolved Raman Spectroscopy
  • 文献类型:   Article
  • 作  者:   XU B, HAO H, HUANG JQ, ZHAO Y, YANG T, ZHANG J, TONG LM
  • 作者关键词:  
  • 出版物名称:   JOURNAL OF PHYSICAL CHEMISTRY C
  • ISSN:   1932-7447 EI 1932-7455
  • 通讯作者地址:  
  • 被引频次:   3
  • DOI:   10.1021/acs.jpcc.2c03372 EA JUN 2022
  • 出版年:   2022

▎ 摘  要

The electron density of state near saddle points in an electronic band structure is greatly enhanced, forming the wellknown Van Hove singularity (VHS), which leads to strengthened electron-photon coupling. However, the VHS-related electron- phonon interaction is rarely studied. Here we report the first observation of intra-mini valley phonon scattering pathways near the saddle points in twisted bilayer graphene (tBLG) through helicity-resolved Raman spectroscopy. Two new second-order Raman modes near the G peak are observed and assigned to combination modes of in-plane optical (TO, LO) and out-of-plane acoustic (ZA) mode, at similar to 1580 cm(-1) (TOZA) and similar to 1595 cm(-1) (LOZA), respectively. The twist-angle-dependence of their intensities and frequencies can be explained by double resonance Raman processes considering the fine electronic band structure of saddle points. Our findings provide a deeper understanding of the electronic band structure at saddle points of tBLG and enrich the VHS-related physics from an electron-phonon interaction point of view.