Impacts of substrate conditions and post-annealing on monolayer iron-based superconductors

High-temperature superconductivity in monolayer FeSe/Fe(Te, Se) grown on $\mathrm{SrTi}{\mathrm{O}}_{3}$ (STO) substrates is closely related to the interface effects from STO. Using in situ low-temperature scanning tunneling microscopy/spectroscopy, we study the surface flatness and reconstructions of STO from different pre-treatment methods, and the influence of STO reconstructions on the interfacial superconductivity. Besides, the impacts from postgrowth annealing conditions on the morphology and superconducting properties of monolayer FeSe/Fe(Te, Se) are investigated. These results pave the way for the growth of high-temperature interface superconductors in a detailed level, and provide useful references for better interfacial engineering to foster superconductivity.