Critical current density and pinning potential in YBa2Cu3O7−δ thick films ablated from a BaZrO3-doped nanocrystalline target
Superconductor Science and Technology, 22 (4):
045014 (5pp) (2009)Zusammenfassung
We report on the pulsed laser deposition and characterization of thick (1.27 um) films ablated from a nanocrystalline YBa2Cu3O7?d (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 density Jc and a three- to four-fold increase in the maximum pinning force in comparison with 1 um thick films grown from a commercial microcrystalline YBCO target, at both 77.3 and 65 K. We have found that the frequency-dependent critical current densities Jc(f0/f) estimated from susceptibility measurements are linear in a double-logarithmic plot (where f is the frequency of the AC field and f0 is a macroscopic attempt frequency of about 106 Hz), consistent with a logarithmic dependence of the pinning potential on the current density, and are again several times higher in nYBCO/BZO thick films. From the slopes of the Jc(f0/f) dependences we have also estimated the values of pinning potentials in fields between 3 and 5 T.