Fast suppression of superconductivity with Fe site Ni substitution in Fe1-xNixSe0.5Te0.5 (x=0.0, 0.01, 0.03, 0.05, 0.07, 0.10 and 0.20) single crystals

TL;DR

This study investigates how Ni doping at Fe sites rapidly suppresses superconductivity in FeSe0.5Te0.5 single crystals, with superconducting transition temperature decreasing significantly as Ni concentration increases.

Contribution

It provides a systematic analysis of the suppression of superconductivity due to Ni doping in FeSe0.5Te0.5 single crystals, highlighting the rapid decrease of Tc with doping.

Findings

Superconductivity is suppressed quickly with Ni doping.

Tc decreases from 12K to 2K as Ni concentration increases.

Superconductivity is not observed beyond 0.07 Ni doping.

Abstract

We report the effect of Ni doping on superconductivity of FeSe0.5Te0.5. The single crystal samples of series Fe1-xNixSe0.5Te0.5 (x=0.0, 0.01, 0.03, 0.05, 0.07, 0.10 and 0.20) are synthesized via vacuum shield solid state reaction route and high temperature heating followed by slow cooling. All the crystals of Fe1-xNixSe0.5Te0.5 series with x up to 0.20, i.e., 20% substitution of Ni at Fe site are crystallized in single phase tetragonal structure with space group P4/nmm. The electrical resistivity measurements revealed that Tc decreases fast with increase of Ni concentration in Fe1-xNixSe0.5Te0.5. Namely the superconducting transition temperature (Tc) being defined as resistivity =0 decrease from 12K to around 4K and 2K for x=0.01 and 0.03 samples respectively. For x=0.05 (5at% Ni at Fe site) though Tconset is observed in resistivity measurements but \r{ho}=0 is not seen down to 2K. For x more than 0.07, neither the Tconset nor Tc\r{ho}=0 is seen down 2K in R-T measurements. It is demonstrated that Ni doping at Fe site in FeSe0.5Te0.5 superconductor suppresses superconductivity fast. The rate of Tc depression is albeit non monotonic. Summarily, a systematic study on suppression of superconductivity with Fe site Ni doping in flux free gown FeSe0.5Te0.5 single crystals is presented in the current communication.