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Self-energy dynamics and mode-specific phonon threshold effect in a Kekulé-ordered graphene
National Science Review ( IF 20.6 ) Pub Date : 2021-09-11 , DOI: 10.1093/nsr/nwab175
Hongyun Zhang 1 , Changhua Bao 1 , Michael Schüler 2 , Shaohua Zhou 1 , Qian Li 1 , Laipeng Luo 1 , Wei Yao 1 , Zhong Wang 3 , Thomas P Devereaux 2 , Shuyun Zhou 1
Affiliation  

Electron-phonon interaction and related self-energy are fundamental to both the equilibrium properties and non-equilibrium relaxation dynamics of solids. Although electron-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 a Kekulé-ordered graphene with folded Dirac cones at the Γ point, we have succeeded in resolving the self-energy effect induced by coupling of electrons to two phonons at Ω1 = 177 meV and Ω2 = 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.

中文翻译:

Kekulé有序石墨烯中的自能动力学和模式特异性声子阈值效应

电子-声子相互作用和相关的自能是固体平衡性质和非平衡弛豫动力学的基础。尽管各种时间分辨测量表明电子 - 声子相互作用对石墨烯的弛豫动力学很重要,但缺乏能量和动量分辨的自能动力学阻碍了特定声子模式在弛豫中的作用的直接识别动力学。在这里,通过对在 Γ 点具有折叠狄拉克锥的 Kekulé 有序石墨烯进行时间和角度分辨光电子能谱测量,我们成功地解决了由电子耦合到 Ω1 = 177 meV 的两个声子引起的自能效应和 Ω2 = 54 meV 并揭示其在时域中的动态变化。而且,
更新日期:2021-09-11
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