Guidelines for optimizing random and correlated pinning in rare-earth-based superconducting films

Pinning in YBa 2 Cu 3 O 7− x (YBCO) films is compared with mixed rare-earth (RE) films. The field dependence of critical current density and pinning force plots at 75.5 K are analysed. The work provides a guideline as to how to optimize pinning by inclusion of both random and correlated defects. In summary, Y mixed with larger RE ions appears to be optimum for effective pinning across a wide field regime as well as permitting growth at temperatures low enough for technological use.