Effects of Zr Doping on Magnetic and Structural Properties of DyBa2Cu3O7-δ Thin Films

DyBa2(Cu1-x -Zr-x)(3) O7-delta thin films (with x = 0.00, 0.02, 0.04, and 0.06) were synthetized using the chemical solution deposition method on single crystalline LaAlO3 substrates. Effects resulting from Zr doping were investigated by means of magnetic and structural measurements. X-ray diffraction analysis demonstrated a strong c-axis orientation in the DyBa2 (Cu1-x Zr-x)(3) O7-delta thin films, with only minor reflections due to the presence of Dy-2 O-3 and BaZrO3 phases. Narrow transitions with Delta T-c ranging from 1 to 2 K for samples with x = 0.00 and 0.06, respectively, were observed in ac magnetic susceptibility curves, where the nondoped sample demonstrated the highest T-C(onset) of 91.7 K compared to the Zr-doped samples. Critical current densities J(c) of the thin films were obtained from magnetization loop measurements with applied magnetic fields up to 6 T and by employing the Bean model. The sampled doped with 4% Zr exhibited the highest J(c) value (J(c) = 3.5 MA/cm(2), self-field, 77 K) in the low field range and we, in general, observed that Zr-doped films demonstrated higher values compared to the pure sample. Pinning force plots (F-p versus B) reveal a significant improvement over the magnetic field range investigated of the maximum pinning force for Zr-doped samples. We found F-P(Max) = 1.7 GN/m(3) and 3.8 GN/m(3) for pure and 6% Zr samples, respectively. Analysis based on the Dew-Hughes model shows that normal surface pinning is the dominating pinning mechanism.