Pulsed laser deposition and in-field characterization of FeTe0.8S0.2 epitaxial thin films with enhanced superconducting properties

Fe–Te–S thin films deposited by pulsed laser deposition at 400 °C on SrTiO3 (1 0 0) and MgO (1 0 0) single crystals showed epitaxy and 4-fold symmetry. Films deposited on both substrates reached zero resistance condition (Tc0=3.54K on STO and 5.37 K on MgO) and presented large upper critical field (Bc2(0) = 61.1 T on STO and 74.2 T for MgO using 90% of the normal state resistance and Werthamer–Helfand–Hohenberg model), indicating that the coherence length ξ0 of the present films is very short (ξ0 = 2.3 nm on STO and 2.1 nm on MgO).