One-step synthesis of KxFe2-ySe2 single crystals for high critical current density

TL;DR

This paper presents a simple one-step method to synthesize KxFe2-ySe2 single crystals with high critical current density and strong magnetic field performance, suitable for practical superconducting applications.

Contribution

The authors developed a straightforward one-step synthesis process with post annealing and quenching to produce homogeneous KxFe2-ySe2 crystals exhibiting high Jc and magnetic field resilience.

Findings

Superconducting transition at ~33 K.

Critical current density up to 1.0×10^5 A/cm^2 at 5 K.

High upper critical fields (~206 T for H//ab).

Abstract

We have established a simple process that allows for the one-step synthesis of KxFe2-ySe2 single crystals, which exhibit high critical current density Jc. The post annealing and quenching technique has improved the homogeneity of as-grown crystals, resulting in full shielding of the external magnetic field. The quenched crystals show a superconducting transition at Tconset = 32.9 K and Tczero = 32.1 K. The upper critical fields \mu_{0}Hc2(0) for H//ab and H//c are estimated to be ~206 and ~50 T, respectively. The critical current densities Jc for H//ab and H//c reach as high as 1.0\times10^{5} and 3.4\times10^{4} A/cm2 at 5 K. Furthermore, Jc exhibits a high field performance and a significantly weak temperature dependence up to 5 T, suggesting strong pinning. These results demonstrate that KxFe2-ySe2 would be a promising candidate material for practical applications.