Self-energy dynamics and the mode-specific phonon threshold effect in Kekulé-ordered graphene  

作　　者：Hongyun Zhang Changhua Bao Michael Schüler Shaohua Zhou Qian Li Laipeng Luo Wei Yao Zhong Wang Thomas P.Devereaux Shuyun Zhou 

机构地区：[1]State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics,Tsinghua University,Beijing 100084,China [2]Stanford Institute for Materials and Energy Sciences(SIMES),SLAC National Accelerator Laboratory,Menlo Park,CA 94025,USA [3]Institute for Advanced Study,Tsinghua University,Beijing 100084,China [4]Department of Materials Science and Engineering,Stanford University,Stanford,CA 94035,USA [5]Frontier Science Center for Quantum Information,Beijing 100084,China

出　　处：《National Science Review》2022年第5期77-84,共8页国家科学评论（英文版）

基　　金：supported by the National Natural Science Foundation of China(11427903 and 11725418);the National Key R&D Program of China(2020YFA0308800 and 2016YFA0301004);the Tsinghua University Initiative Scientific Research Program and the Tohoku-Tsinghua Collaborative Research Fund;Beijing Advanced Innovation Center for Future Chip(ICFC);financial support from the U.S.Department of Energy(DOE),Office of Basic Energy Sciences,Division of Materials Sciences and Engineering,under Contract No.DEAC02-76SF00515;the Alexander von Humboldt Foundation for its support with a Feodor Lynen scholarship。

摘　　要：Electron-phonon interaction and related self-energy are fundamental to both the equilibrium properties and non-equilibrium relaxation dynamics of solids.Although ele ctron-phonon interaction has been suggested by various time-resolved measurements to be important for the relaxation dynamics of graphene,the lack of energy-and momentum-resolved self-energy dynamics prohibits direct identification of the role of specific phonon modes in the relaxation dynamics.Here,by performing time-and angle-resolved photoemission spectroscopy measurements on Kekulé-ordered graphene with folded Dirac cones at theΓpoint,we have succeeded in resolving the self-energy effect induced by the coupling of electrons to two phonons atΩ;=177 meV andΩ;=54 meV,and revealing its dynamical change in the time domain.Moreover,these strongly coupled phonons define energy thresholds,which separate the hierarchical relaxation dynamics from ultrafast,fast to slow,thereby providing direct experimental evidence for the dominant role of mode-specific phonons in the relaxation dynamics.

关 键 词：TrARPES SELF-ENERGY electron-phonon coupling Kekulé-ordered graphene 

分 类 号：O469[理学—凝聚态物理] TQ127.11[理学—电子物理学]