YBa2Cu3O7-d Films with a Nanoparticulate Dispersion of Y2BaCuO5 for Enhanced Flux Pinning (Preprint).

摘要

A comparison study of YBa2Cu3O7-x (Y123) films incorporating a nano- particulate dispersion of second-phase Y2BaCuO5 (Y211) and Y123 films incorporating a material (X, not specified) more closely lattice matched with Y123 is given. The inclusion of the nano-particulate dispersion was for the purpose of increasing superconducting film's magnetic pinning strength with the resultant improved in-field critical current density. The Y211 particulate and X layered inclusions in the Y123 was accomplished with multiple consecutive depositions by pulsed laser ablation of the respective targets on LaAlO3 substrates. Results substantiate growth of the Y211 was caused by lattice mismatching with the Y123 achieving a Y211 particle size of approximately 10-20 nm in diameter and approximately 4 nm in height. The Y123 phase maintained excellent epitaxy with high in-plane orientation with both Y211 and X materials. With the Y211 additions, the critical current densities of the films increased 3-5 times at applied magnetic fields of 1.6 T from 30 to 77 K as compared to high quality Y123 films with no Y211 additions. The lattice matched material resulted in degraded currents in applied magnetic fields although self-field values were on par with plain Y123. This may imply a possible nullification of the intrinsic Y123 pinning mechanisms with the X material interlayers.