Critical current density and pinning potential inYBa2Cu3O7−δ thick filmsablated from a BaZrO3-doped nanocrystalline target

Abstract

We report on the pulsed laser deposition and characterization of thick(1.27 µm) films ablated from ananocrystalline YBa2Cu3O7−δ (YBCO)target doped with 4 wt% BaZrO3 (BZO), nYBCO/BZO. DC magnetization measurements have shown a four- to five-fold increase in the critical current densityJc and a three- to four-fold increase in the maximum pinning force in comparison with1 µm thick films grown from a commercial microcrystalline YBCO target, at both 77.3and 65 K. We have found that the frequency-dependent critical current densitiesJc(f0/f) estimated from susceptibility measurements are linear in a double-logarithmic plot (wheref is the frequency ofthe AC field and f0 is a macroscopic attempt frequency of about106 Hz), consistent with a logarithmic dependence of the pinningpotential on the current density, and are again several times higher innYBCO/BZO thick films. Fromthe slopes of the Jc(f0/f) dependences we have also estimated the values of pinning potentials in fields between 3 and5 T.