Upper critical fields and superconducting anisotropy of K0.70Fe1.55Se1.01S0.99 and K0.76Fe1.61Se0.96S1.04 single crystals

TL;DR

This study examines how sulfur doping affects the upper critical fields and anisotropy in K-Fe-Se-S single crystals, revealing increased anisotropy and potential changes in electronic dimensionality.

Contribution

It provides new insights into the effects of sulfur substitution on superconducting properties and anisotropy in K-Fe-Se-S compounds.

Findings

Upper critical fields decrease with S content.

Anisotropy of Hc2(T) increases with S doping.

Magnetoresistivity scales with anisotropic Ginzburg-Landau theory.

Abstract

We have investigated temperature and angular dependence of resistivity of K0.70(7)Fe1.55(7)Se1.01(2)S0.99(2) and K0.76(5)Fe1.61(5)Se0.96(4)S1.04(5) single crystals. The upper critical fields Hc2(T) for both field directions decrease with the increase in S content. On the other hand, the angle-dependent magnetoresistivity for both compounds can be scaled onto one curve using the anisotropic Ginzburg-Landau theory. The obtained anisotropy of Hc2(T) increases with S content, implying that S doping might decrease the dimensionality of certain Fermi surface parts, leading to stronger two dimensional character.