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

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 μ_{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.

10 pages, 5 figures

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• Superconductivity and magnetism in RbxFe2-ySe2: Impact of thermal treatment on mesoscopic phase separation
• Robust superconductivity and transport properties in (Li1-xFex)OHFeSe single crystals
• Origin of the Higher-$T_\rm{c}$ Phase in the K${}_x$Fe${}_{2-y}$Se${}_2$ System
• Evolution of superconductivity in isovalent Te-substituted KxFe2-ySe2 crystals
• Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor
• Direct Observation of Microstructures on Superconducting Single Crystals of K${}_x$Fe${}_{2-y}$Se${}_2$
• Phase-separation control of K${}_x$Fe${}_{2-y}$Se${}_2$ superconductor through rapid-quenching process
• Annealing Effect on Microstructure and Superconductivity of KxFeySe2 Synthesized by an Easy One-step Method
• Quenching Dependence on Superconductivity in the Synthesizing Process of Single Crystals of Rb${}_x$Fe${}_{2-y}$Se${}_2$