石墨的声子表面映射：准简并声子色散的解纠缠
Phonon surface mapping of graphite: disentangling quasi--degenerate phonon dispersions
摘要：
本文用非弹性X射线散射法对石墨$K$点附近的声子色散进行了二维映射。目前的工作解决了长期存在的问题有关的正确分配的横向和纵向声子分支在$K$。我们观察到三个TO，LA和LO导出的声子分支的几乎简并和一个强的声子三角弯曲。相关效应使TO模的Kohn反常重正化，TO模表现出与电子能带结构相反的三角弯曲效应。我们确定的电子-声子耦合常数为166 $\rm(eV/Å)^2$在良好的协议$GW$计算。这些结果是理解角分辨光电发射，双共振拉曼和输运测量的石墨烯为基础的系统的基础。
英文摘要：
The two-dimensional mapping of the phonon dispersions around the $K$ point of graphite by inelastic x-ray scattering is provided. The present work resolves the longstanding issue related to the correct assignment of transverse and longitudinal phonon branches at $K$. We observe an almost degeneracy of the three TO, LA and LO derived phonon branches and a strong phonon trigonal warping. Correlation effects renormalize the Kohn anomaly of the TO mode, which exhibits a trigonal warping effect opposite to that of the electronic band structure. We determined the electron--phonon coupling constant to be 166$\rm(eV/Å)^2$ in excellent agreement to $GW$ calculations. These results are fundamental for understanding angle-resolved photoemission, double--resonance Raman and transport measurements of graphene based systems.
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