Magneto-optical characterizations of FeTe$_{0.5}$Se$_{0.5}$ thin films with critical current density over 1 MA/cm$^2$

TL;DR

This study uses magneto-optical imaging to analyze FeTe$_{0.5}$Se$_{0.5}$ thin films, revealing high critical current densities and enhanced superconducting transition temperatures, promising for practical applications.

Contribution

It provides the first detailed magneto-optical characterization of FeTe$_{0.5}$Se$_{0.5}$ thin films with high critical current density over 1 MA/cm$^2$.

Findings

Critical current density exceeds 1 MA/cm$^2$ at 5 K.

Superconducting transition temperature is about 19 K, higher than bulk.

Magnetic flux penetration indicates isotropic current distribution.

Abstract

We performed magneto-optical (MO) measurements on FeTe$_{0.5}$Se$_{0.5}$ thin films grown on LaAlO$_3$ (LAO) and Yttria-stabilized zirconia (YSZ) single-crystalline substrates. These thin films show superconducting transition temperature, ${T_c}$ $\sim$ 19 K, 4 K higher than the bulk sample. Typical roof-top patterns can be observed in the MO images of thin films grown on LAO and YSZ, from which a large and homogeneous critical current density, ${J_c}$, over 1 $\times$ 10$^6$ A/cm$^2$ at 5 K was obtained. Magnetic flux penetration measurement reveals that the current is almost isotropically distributed in the two thin films. Compared with bulk crystals, FeTe$_{0.5}$Se$_{0.5}$ thin film demonstrates not only higher ${T_c}$, but also much larger ${J_c}$, which is attractive for applications.