Effects of Te- and Fe-doping on the superconducting properties in FeySe1-xTex thin films

High quality FeySe1-xTex epitaxial thin films have been fabricated on TiO2-buffered SrTiO3 substrates by pulsed laser deposition technology. There is a significant composition deviation between the nominal target and the thin film. Te doping can affect the Se/Te ratio and Fe content in chemical composition. The superconducting transition temperature T-c is closely related to the chemical composition. Fe vacancies are beneficial for the FeySe1-xTex films to exhibit the higher T-c. A 3D phase diagram is given that the optimize range is x = 0.13-0.15 and y = 0.73-0.78 for FeySe1-xTex films. The anisotropic, effective pining energy, and critical current density for the Fe0.72Se0.94Te0.06, Fe0.76Se0.87Te0.13 and Fe0.91Se0.77Te0.23 films were studied in detail. The scanning transmission electron microscopy images display a regular atomic arrangement at the interfacial structure.

Automated summary

High quality FeySe1-xTex epitaxial thin films were fabricated using pulsed laser deposition technology. The chemical composition was affected by Te doping and the presence of Fe vacancies enhanced the superconducting transition temperature. The anisotropy, effective pining energy, and critical current density of the films were investigated.