Potassium fluoride doped LaOFeAs multiband superconductors: Evidence for extremely high upper critical field

TL;DR

This paper introduces a new synthesis method for LaOFeAs superconductors using potassium fluoride, resulting in higher critical temperature and upper critical field, advancing multiband superconductor research.

Contribution

It presents a novel synthesis route with potassium fluoride, leading to record high critical temperature and upper critical field in LaOFeAs superconductors.

Findings

Highest Tc onset of 28.5K reported

Record upper critical field achieved

Effective potassium substitution enhances superconducting properties

Abstract

We describe a new methodology of synthesizing the oxypnictide superconductors with potassium fluoride as a source as a source of fluorine instead of LaF3. This route also allows the substitution of potassium at lanthanum sites which leads to an increase in the upper critical field as would be expected for a multiband superconductor. We also report the highest reported Tc onset of 28.5K and highest upper critical field in these superconductors.