Magneto-optical characterizations of FeTe0.5Se0.5 thin films with critical current density over 1 MA cm−2

We performed magneto-optical (MO) measurements on FeTe0.5Se0.5 thin films grown on LaAlO3 (LAO) and Yttria-stabilized zirconia (YSZ) single-crystalline substrates. These thin films show superconducting transition temperature Tc ∼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 Jc over 1 × 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, FeTe0.5Se0.5 thin film demonstrates not only higher Tc, but also much larger Jc, which is attractive for applications.