High quality epitaxial FeSe0.5Te0.5 thin films grown on SrTiO3 substrate by Pulsed Laser Deposition

Superconducting epitaxial FeSe0.5Te0.5 thin films were prepared on SrTiO3 (001) substrates by pulsed laser deposition. The high purity of the phase, the quality of the growth and the epitaxy were studied with different experimental techniques: X-Rays Diffraction, Reflection High Energy Electron Diffraction, Scanning Tunnel Microscope and Atomic Force Microscope. The substrate temperature during the deposition was found to be the main parameters governing sample morphology and superconducting critical temperature. Films obtained in the optimal conditions show an epitaxial growth with c axis perpendicular to the film surface and the a and b axis parallel to the substrates one, without the evidence of any other orientation. Moreover, such films show a metallic behavior over the whole measured temperature range and critical temperature above 17K, which is a value higher than the target one.