Pinning analyses of a BaHfO3-containing GdBa2Cu3O7-δ 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 μ0H = 19 T. The exponent n of the electric field-current density characteristics ( E∝ Jn) depends on critical current density Jc as (n-1) ∝ Jcα (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 Jc 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 Jc 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.