Correlated pinning behavior in ErBa 2Cu 3O y films with BaZrO 3 nano-rods

Abstract

In REBa 2Cu 3O y (RE123) films with BaZrO 3 (BZO), the columnar shaped BZO precipitates, called nano-rods, are formed as the c-axis-correlated pinning centers. In order to understand the vortex pinning properties of RE123 films with BZO nano-rods, we measured the resistivity ρ and critical current density J c of three different films, i.e. the Er123 films with 0, 1.5 and 3.5 wt% BZO prepared by pulsed laser deposition. We found that the peak related to the c-axis-correlated pinning in the angular dependence of J c became large in a low field region but small in a high magnetic field with increasing BZO concentration. In addition, the irreversibility field at B|| c-axis increased also with increasing BZO concentration, although the dip in the angular dependence of ρ and the peak of the J c at B|| c-axis decreased in the high magnetic field near the irreversible field. It is suggested that the BZO addition is effective to the enhancement of J c in a low field region as well as the improvement of the irreversibility field. However, we have to consider the c-axis-correlated pinning by the edge dislocations as well as the nano-rods in order to understand it in a high field region.