An Atomic Force Microscopy Study of Single-Layer FeSe Superconductor
The single-layer iron selenide (FeSe) superconductor is becoming an ideal system to study the mechanism of high-temperature superconductivity. In this work, we use atomic force microscopy (AFM) to demonstrate that: (1) unidirectional stripe in the single-layer FeSe film is purely an electronic feature instead of lattice reconstruction; (2) the charge transfer from the SrTiO3 substrate to FeSe plays an important role in inducing superconductivity in single-layer FeSe. Both short-range and long-range forces are exploited in the study. The combination of AFM with scanning tunneling microscopy opens a new opportunity to investigate the mechanism of high-Tc materials.