Superconductivity above 28 K in single unit cell FeSe films interfaced with GaO$_{2-\delta}$ layer on NdGaO$_{3}$(110)

TL;DR

This study demonstrates that single unit cell FeSe films on GaO$_{2-\delta}$ layers on NdGaO$_{3}$(110) exhibit interface-enhanced superconductivity with an onset temperature of about 28 K, significantly higher than bulk FeSe.

Contribution

It reports the discovery of high-temperature superconductivity in FeSe films interfaced with GaO$_{2-\delta}$, providing a new platform for understanding interface effects in superconductivity.

Findings

Superconductivity with an onset temperature of about 28 K observed.

FeSe films are electron doped via interface charge transfer.

The heterostructure is comparable to FeSe/TiO$_{2-\delta}$ systems.

Abstract

We prepared single unit cell FeSe films on GaO$_{2-\delta}$ terminated perovskite NdGaO$_{3}$(110) substrates and performed ex situ transport and scanning transmission electron microscopy measurements on the FeTe protected films. Our experimental measurements showed that the single unit cell FeSe films interfaced with GaO$_{2-{\delta}}$ layer are electron doped via interface charge transfer. Most importantly, this type of heterostructure can host interface enhanced superconductivity with an onset temperature of about 28 K, which is much higher than the value of 8 K in bulk FeSe. Our work indicates that FeSe/GaO$_{2-{\delta}}$can be a comparative platform with the FeSe/TiO$_{2-{\delta}}$ family for understanding the mechanism of interface enhanced high temperature superconductivity.