Residual stress and strain on microstructure evolutions and superconductivity of REBa₂Cu₃O_7−δ films grown by trifluoroacetate metal organic deposition

This research studies the effects of the residual stress and strain on the microstructure, critical current density, transition temperature, and microwave surface resistance of REBa₂Cu₃O_7−δ (RE, rare earth) thin films grown by trifluoroacetate metal organic deposition. Different concentrations of Dy are introduced into YBa₂Cu₃O_7−δ superconducting thin films. The superconducting transition temperature increases with an increase in the internal strain, while the critical current density exhibits an inverse variation relationship with the residual stress and c-axis length. The current carrying capability of REBa₂Cu₃O_7−δ thin films can be improved by doping with appropriate Dy concentrations, which can be determined based on the residual stress modulation in the REBa₂Cu₃O_7−δ thin films. In addition, no apparent transition of tensile or compressive stresses is observed in the thin films during the residual stress measurements. This paper provides a useful theoretical guidance for effectively improving the superconductivity of REBa₂Cu₃O_7−δ thin films.