Low-temperature synthesis of FeTe_0.5Se_0.5polycrystals with a high transport critical current density

Abstract

We have prepared high-quality polycrystalline FeTe0.5Se0.5 at temperature as\nlow as 550{\\deg}C. The transport critical current density evaluated by the\ncurrent-voltage characteristics is over 700 A/cm2 at 4.2 K under zero field,\nwhich is several times larger than FeTe0.5Se0.5 superconducting wires. The\ncritical current density estimated from magneto-optical images of flux\npenetration is also similar to this value. The upper critical field of the\npolycrystalline FeTe0.5Se0.5 at T = 0 K estimated by\nWerthamer-Helfand-Hohenberg theory is 585 kOe, which is comparable to that of\nsingle crystals. This study gives some insight into how to improve the\nperformance of FeTe0.5Se0.5 superconducting wires.\n