Uniform Oxygen Doping Leads to Superconductivity in FeTe Films

TL;DR

This study shows that uniform interstitial oxygen doping in FeTe films induces superconductivity, highlighting the importance of doping method and oxygen distribution for achieving homogeneous superconducting properties.

Contribution

It demonstrates that interstitial oxygen, uniformly incorporated post-growth, is responsible for superconductivity in FeTe films, clarifying the doping mechanism.

Findings

Interstitial oxygen induces superconductivity in FeTe.

Homogeneous oxygen diffusion correlates with superconductivity.

Superconductivity is spatially uniform, not filamentary.

Abstract

FeTe is known to become a superconductor when doped with oxygen. Using layer by layer growth of single crystal films by molecular beam epitaxy (MBE), we have studied how oxygen incorporates. If oxygen is supplied during growth of a layer, it substitutes for tellurium inhomogeneously in oxygen domains that are not associated with superconductivity. When oxygen is supplied after growth, it diffuses homogeneously into the crystalline film and incorporates interstitially. Only the interstitial oxygen causes superconductivity to emerge. This suggests that the superconductivity observed in this material is spatially uniform and not filamentary.