Abstract We study the correction of the effective mass of the surface polaron in monolayer FeSe on SrTiO 3 substrate using a variational approach, in which surface polaron states are formed arising from the coupling between electrons in FeSe film and two kinds of surface optical (SO) phonon modes in SrTiO 3 substrate. We give a concise formula for the relations of the effective masses with the electron–SO phonon coupling matrixes, and find that the effective masses are enhanced significantly due to these coupling, which are very good agreement with the recent experimental measurements. Moreover, the effective masses depend strongly on the cutoff wave vectors of SO phonon modes and the interlayer distance between FeSe and SrTiO 3 substrate. Our theoretical results provide a practical route to analyze the electron–SO phonon coupling by measuring the variation of effective masses in experiments.

中文翻译：

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SrTiO3衬底上FeSe薄膜表面极化子有效质量的提高

摘要 我们使用变分方法研究了 SrTiO 3 衬底上单层 FeSe 表面极化子有效质量的校正，其中 FeSe 薄膜中的电子与两种表面光学 (SO) 耦合形成表面极化子态。 SrTiO 3 衬底中的声子模式。我们给出了有效质量与电子-SO 声子耦合矩阵之间关系的简明公式，并发现由于这些耦合，有效质量显着增强，这与最近的实验测量非常吻合。此外，有效质量很大程度上取决于 SO 声子模式的截止波矢量以及 FeSe 和 SrTiO 3 衬底之间的层间距离。