Investigation of the FeSe/SrTiO3 interface using Atom Probe Tomography*

Monlayer FeSe on SrTiO3 (FeSe/STO) is a high temperature superconductor with Tc above 100 K. Although scanning tunneling microscopy (STM) imaging has characterized its surface in detail, the content and behavior in the FeSe/STO interface remains unclear. Characterizing the interface is important to gain further understanding on the mechanism for the unexpected high-temperature superconductivity in this system. Techniques such as scanning transmission electron microscopy (STEM) have been used to demonstrate that the interface structure is correlated with the material’s superconducting properties, however much remains unclear about the specific composition and behavior of the interface. Here we characterize the interface using atom probe tomography (APT), which reveals the structural and chemical properties of the FeSe/STO interface and provides insight into the origin of the material’s superconductivity.