A new approach for improving global critical current density in Fe(Se0.5Te0.5) polycrystalline materials

TL;DR

This paper introduces a novel melting and annealing method for producing homogeneous, dense Fe(Se0.5Te0.5) superconducting samples with significantly improved critical current density and magnetic properties compared to traditional techniques.

Contribution

The study presents a new preparation process that enhances the critical current density and magnetic performance of Fe(Se0.5Te0.5) bulk superconductors, outperforming existing methods.

Findings

Critical current density reaches about 10^3 A/cm^2 at 4.2 K and zero field.

Samples exhibit high upper critical fields and sharp superconducting transitions.

Field dependence of critical current density is very weak, maintaining high values under strong magnetic fields.

Abstract

A novel method to prepare bulk Fe(Se0.5Te0.5) samples is presented, based on a melting process and a subsequent annealing treatment. With respect to the standard sintering technique, it produces much more homogeneous and denser samples, characterized by large and well interconnected grains. The resulting samples exhibit optimal critical temperature values, sharp resistive and magnetic transitions, large magnetic hysteresis loops and high upper critical fields are observed. Interestingly, the global critical current density is much enhanced as compared to the values reported in literature for bulk samples of the same 11 family, reaching about 103 A/cm2 at zero field at 4.2 K as assessed by magnetic, transport and magneto-optical techniques. Even more importantly, its field dependence turns out to be very weak, such that at \mu_{0}H = 7 T it is suppressed only by a factor \sim2.