论文标题
在谐振非弹性X射线散射实验中的色散光音子理论
Theory of dispersive optical phonons in resonant inelastic x-ray scattering experiments
论文作者
论文摘要
该社区目前缺乏对固体中电子 - phonon（$ e $ ph）相互作用的共鸣X射线散射（RIXS）如何探索固体中的相互作用。例如，此过程的大多数理论模型都集中在无散的爱因斯坦声子上。使用最近开发的动量平均（MA）变分近似来计算带绝缘子的RIX光谱，我们检查了电子和声子分散体在散射过程的中间状态下的影响。我们发现，即使是非动量的电子 - 音波耦合，即使在RIX强度中，它们的包含及其相互作用也引入了RIX强度的显着动量变化。声子色散还引起激发线形状的非平凡变化，这可能会对数据分析产生定量影响。这些结果突出了解释实际材料中RIX数据的巨大挑战。
The community currently lacks a complete understanding of how resonant inelastic x-ray scattering (RIXS) experiments probe the electron-phonon ($e$-ph) interaction in solids. For example, most theoretical models of this process have focused on dispersionless Einstein phonons. Using a recently developed momentum average (MA) variational approximation for computing RIXS spectra of band insulators, we examine the influence of both electron and phonon dispersion in the intermediate state of the scattering process. We find that the inclusion of either, and their mutual interplay, introduces significant momentum variations in the RIXS intensity, even for momentum-independent electron-phonon coupling. The phonon dispersion also induces nontrivial changes in the excitation line shapes, which can have a quantitative impact on the data analysis. These results highlight the considerable challenges of interpreting RIXS data in actual materials.
