Comparative study of Fe(Se,Te) thin films on flexible coated conductor templates and single-crystal substrates

In this paper, we compare epitaxial Fe(Se,Te) thin films grown by pulsed laser deposition on CaF 2 , SrTiO 3 , MgO single crystals as well as on different metallic templates having a CeO 2 based top surface. In particular, we performed a detailed structural and superconducting analysis. X-ray diffraction studies showed highly textured films on all templates. The superconducting transition temperatures are between 21 K and 14 K for Fe(Se,Te) films on CaF 2 and on MgO single-crystal substrates, respectively, whereas films on the metal templates show T c values up to 18 K. The critical current density ( J c ) was determined from magnetization loops in fields up to 7 T. Calculations in the framework of the extended critical state model showed J c values over 2 MA cm −2 and 0.9 MA cm −2 at 5 K in self-field on single-crystal substrates and metal templates substrates, respectively. Detailed transmission electron microscopy studies reveal smooth layers on all templates. Whereas small defects were found in films on single crystals, pronounced grain boundaries with higher misorientation angle were visible in the layers on metallic templates.