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

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.

13 pages, 7 figures