Characterization of superconducting SmBa₂Cu₃O₇ films grown by pulsed laser deposition

We have investigated epitaxial superconducting SmBa₂Cu₃O₇ (Sm123) films grown by pulsed-laser deposition on single-crystal SrTiO₃ substrates. The deposition temperature plays an important role in determining the superconducting properties of Sm123 films. The superconducting transition temperature increases with the deposition temperature whereas the transition width decreases at deposition temperatures in the range of 700-875°C. A Sm123 film deposited at 850°C exhibits a transition temperature above 93 K with a transition width less than 0.5 K. Even though Sm123 films exhibit a higher transition temperature than YBa₂Cu₃O₇(Y123), the Sm123 shows lower critical current density at liquid-nitrogen temperature. The nominal critical current density of Sm123 film is less than 1 MA/cm² at 75.4 K. Nevertheless, the Sm123 films have less anisotropy and stronger pinning characteristics compared to Y123. They are also much smoother with fewer particulates, as revealed by scanning electron microscopy.