Superconductivity of FeSe0.5Te0.5 Thin Films Grown by Pulsed Laser Deposition

FeSe0.5Te0.5 thin films with PbO-type structure are successfully grown on MgO(100) and LaSrAlO4(001) substrates from FeSe0.5Te0.5 or FeSe0.5Te0.75 polycrystalline targets by pulsed-laser deposition. The film deposited on the MgO substrate (film thickness ~ 55 nm) shows superconductivity at 10.6 K (onset) and 9.2 K (zero resistivity). On the other hand, the film deposited on the LaSrAlO4 substrate (film thickness ~ 250 nm) exhibits superconductivity at 5.4 K (onset) and 2.7 K (zero resistivity). This suggests the strong influence of substrate materials and/or the c-axis length to superconducting properties of FeSe0.5Te0.5 thin films.