Flux Pinning Enhancement of YBCO Films by Y and Ba Site Doping at Minute Concentrations

Abstract

AbstractYBa2Cu3O7-x (Y123) superconducting thin films can maintain high critical current densities in applied magnetic fields up to a few Tesla at 77 K. Even so, this does not preclude the intentional addition of alternate flux pinning centers in the Y123 films to further optimize their in-field Jc. Unfortunately, many methods to incorporate flux pinning centers into Y123 thin films introduce additional steps and/or re-optimization of the deposition parameters for a given addition. Identifying potential additions that can optimize the performance of YBCO films without changing the deposition conditions would be ideal. The work presented here is an extension of earlier work and demonstrates new dopants and possibilities for introducing pinning centers by the route of minute doping or nanodoping. Preliminary results of a study to determine if minute doping can be performed with smaller lanthanide atoms (Tm, Lu), non-lanthanide atoms (Sc) and Ba-site substitution (Sr) are presented. All samples were deposited under identical conditions as pure YBCO. The new dopants will be discussed in addition to those previously presented (Tb, Pr, Ce, Nd, and La). Critical current density data will be presented for 65 K and 77 K in fields up to 9T in addition to new structural data obtained by cross-sectional TEM.