Pinning analyses of a BaHfO3-containing GdBa2Cu3O7-d thin film grown by chemical solution deposition

The electric transport properties of a GdBa2Cu3O 7 − δ thin film containing 12 mol% nano-sized BaHfO3 (BHO) particles grown by chemical solution deposition were investigated in a wide range of temperatures (4.2 ≤T ≤ 77 K) and magnetic fields up to μ 0 H = 19 T. The exponent n of the electric field–current density characteristics ( E ∝ J n ) depends on critical current density J c as (n–1) ∝ J c α (α ∼ 0.45) irrespective of measurement temperature for H ∥ c. On the other hand, this relation does not hold for H ∥ ab. The angular dependence of J c is almost similar to that of n except for the angle close to the ab-plane. A dip of n around this angle regime was observed below 77 K, whereas J c exhibited a maximum. At T ≤ 50 K a tiny peak in the dip was observed that increases with decreasing temperatures. These results suggest that the pinning mechanism changes with temperature for H ∥ ab.