Magic Doping and Robust Superconductivity in Monolayer FeSe on Titanates

TL;DR

This study demonstrates that inserting LaTiO3 layers between monolayer FeSe and SrTiO3 maintains robust superconductivity despite significant charge transfer, revealing an intrinsic magic doping mechanism that could guide high-temperature superconductor design.

Contribution

It introduces a novel interfacial engineering approach using LaTiO3 layers to achieve stable superconductivity in monolayer FeSe, uncovering an intrinsic magic doping phenomenon.

Findings

Superconductivity remains robust despite increased charge transfer.

LaTiO3 layers induce a magic doping level in FeSe.

Interfacial chemical potential modulation does not suppress superconductivity.

Abstract

The enhanced superconductivity in monolayer FeSe on titanates opens a fascinating pathway towards the rational design of high-temperature superconductors. Utilizing the state-of-the-art oxide plus chalcogenide molecular beam epitaxy systems in situ connected to a synchrotron angle-resolved photoemission spectroscope, epitaxial LaTiO3 layers with varied atomic thicknesses are inserted between monolayer FeSe and SrTiO3, for systematic modulation of interfacial chemical potential.With the dramatic increase of electron accumulation at the LaTiO3-SrTiO3 surface, providing a substantial surge of work function mismatch across the FeSe-oxide interface, the charge transfer and the superconducting gap in the monolayer FeSe are found to remain markedly robust. This unexpected finding indicates the existence of an intrinsically anchored magic doping within the monolayer FeSe systems.