Low-temperature fabrication of superconducting FeSe thin films by pulsed laser deposition

Superconducting FeSe thin films were prepared at a substrate temperature of 320 °C by pulsed laser deposition. X-ray diffraction and transmission electron microscopic analyses showed that highly c-axis-orientated and high-quality films were obtained on various substrate materials, including single-crystal MgO, LaAlO₃, SrTiO₃ and (100)-Si, and amorphous-SiO_x, at such low temperature. From transport measurements all the films showed low-temperature structural phase transition at ∼ 60-90 K and superconducting transition at onset temperature varies from ∼ 7 K to < 2 K, depending on the substrate used. The transport property of FeSe film on Si was found most different from all the others, in spite of their similarity in structural analysis. Chemical analysis demonstrated that Fe and Se homogeneously distributed in the film and the stoichiometry of FeSe and the bonding states of Fe and Se are as well uniform along the film growth direction.