DC transport properties of epitaxial superconducting SmBa2Cu3O7-x films

Dc transport properties of high quality c-axis oriented superconducting SmBa2Cu3O7-x (Sm123) films have been investigated in order to understand the pinning mechanism in this material. The Sm123 films have been deposited on both (1 0 0) SrTiO3 and LaAlO3 single-crystal substrates by a dc sputtering technique in high oxygen partial pressure. Structural characterization was carried out by means of X-ray analysis, scanning electron microscopy and atomic force microscopy. The electrical resistivity as a function of temperature of the as grown samples showed a metallic behavior in the normal state and a superconducting transition with Tc(R=0)=92 K and DTc < 3 K. Critical current density measured at 77 K and in self-field was of the order of 106 A/cm2. The temperature dependence of the current-voltage (I-V ) characteristics of the Sm123 films have been measured. The pinning properties have been analysed by examining the activation energy dependence on temperature and bias current density within a thermally activated vortex motion model. We found that experimental data are consistent with a logarithmic-like behavior of the pinning potential.