Impact of Fe site Co substitution on superconductivity of Fe1-xCoxSe0.5Te0.5 (x = 0.0 to 0.10): A flux free single crystal study

TL;DR

This study investigates how substituting Fe with Co in FeSe0.5Te0.5 single crystals affects their structure and superconducting properties, revealing a decrease in Tc with increased Co content and eventual suppression of superconductivity.

Contribution

It provides detailed synthesis, structural analysis, and superconducting property measurements of Co-doped FeSe0.5Te0.5 single crystals, highlighting the impact of Co substitution on superconductivity.

Findings

Superconducting Tc decreases with increasing Co content.

Lattice parameters shrink as Co concentration increases.

Superconductivity is suppressed at x=0.10 Co doping.

Abstract

We report synthesis of Co substitution at Fe site in Fe1-xCoxSe0.5Te0.5 (x=0.0 to 0.10) single crystals via vacuum shield solid state reaction route using flux free method. Single crystal XRD results showed that these crystals grow in (00l) plane i.e., orientation in c-direction. All the crystals possess tetragonal structure having P4/nmm space group. Detailed scanning electron microscopy (SEM) images show that the crystals are grown in slab-like morphology. The EDAX results revealed the final elemental composition to be near stoichiometric. Powder X-Ray diffraction (PXRD) Rietveld analysis results show that (00l) peaks are shifted towards higher angle with increasing Co concentration. Both a and c lattice parameters decrease with increasing Co concentration in Fe1-xCoxSe0.5Te0.5 (x=0.0 to 0.10) single crystals. Low temperature transport and magnetic measurements show that the superconducting transition temperature (Tc), decreases from around 12K to 10K and 4K for x=0.03 and x=0.05 respectively. For x=0.10 crystal superconductivity is not observed down to 2K.