Epitaxial Growth of FeSe0.5Te0.5 Thin Films on CaF2 Substrates with High Critical Current Density

In-situ epitaxial growth of FeSe0.5Te0.5 thin films is demonstrated on a nonoxide substrate CaF2. Structural analysis reveals that compressive stress is moderately added to 36-nm-thick FeSe0.5Te0.5, which pushes up the critical temperature to above 15 K, showing higher values than that of bulk crystals. The critical current density at T = 4.5 K reaches 5.9 x 10(4) A cm(-2) at mu H-0 = 10 T, and 4.2 x 10(4) A cm(-2) at mu H-0 = 14 T. These results indicate that fluoride substrates have high potential for the growth of iron-based superconductors in comparison with popular oxide substrates. (C) 2011 The Japan Society of Applied Physics