Interface enhanced superconductivity in FeSe/SrTiO$_{3}$ and the hidden nature

Abstract

The superconductivity confined in a two-dimensional interface exhibits many exotic phenomena that have certain counterparts in layered cuprates and iron-based superconductors, and thus provides rare opportunities to reveal the mystery of high temperature superconductivity therein. By constructing and tailoring hybrid heterostructures such as FeSe/$\mathrm{SrTiO}_3$ (FeSe/STO), interface-enhanced superconductivity arouses, and the substrate has been demonstrated to provide the phonons and enhance the strong electron–phonon coupling (EPC) within monolayer FeSe. More research and reporting systems uncover that the band-bending induced charge transfer at the interface could become a unified microscopic picture to design the new interface superconductors. With re-examination of the experimental research in $\mathrm{LaAlO}_3$/STO (LAO/STO) and unconventional superconductors, the common characteristics such as band bending and rigid band shift are perceived in the FeSe/STO, LAO/STO and cuprate superconductors. This review may provide important information to inspect the mechanism of high-$T_c$ superconductivity from a different view.

Keywords

• Interface superconductivity
• FeSe/SrTiO$_3$
• Band bending
• Rigid shift
• Electron–phonon coupling
• High-$T_c$ superconductivity