High-temperature superconductivity in single-unit-cell FeSe films on anatase TiO2(001)

TL;DR

This study demonstrates high-temperature superconductivity in single-unit-cell FeSe films on anatase TiO2(001), highlighting the substrate's role and ruling out oxygen vacancies as primary charge transfer sources.

Contribution

It provides new insights into the interfacial mechanisms enabling high-$T_c$ superconductivity in FeSe/TiO2 heterostructures, emphasizing substrate effects and charge transfer processes.

Findings

Superconductivity observed at high temperatures in FeSe/TiO2 films.

Substrate properties critically influence superconductivity.

Oxygen vacancies have limited impact on charge transfer.

Abstract

We report on the observation of high-temperature ($T_\textrm{c}$) superconductivity and magnetic vortices in single-unit-cell FeSe films on anatase TiO$_2$(001) substrate by using scanning tunneling microscopy. A systematic study and engineering of interfacial properties has clarified the essential roles of substrate in realizing the high-$T_\textrm{c}$ superconductivity, probably via interface-induced electron-phonon coupling enhancement and charge transfer. By visualizing and tuning the oxygen vacancies at the interface, we find their very limited effect on the superconductivity, which excludes interfacial oxygen vacancies as the primary source for charge transfer between the substrate and FeSe films. Our findings have placed severe constraints on any microscopic model for the high-$T_\textrm{c}$ superconductivity in FeSe-related heterostructures.