Practical Magnetic Pinning in YBCO

Iron-containing oxide inclusions have been incorporated as nanoscale ferromagnetic precipitate flux pinning centers within pulsed laser deposited YBa2Cu3O7-delta (YBCO) thin films via a simple process utilizing a composite deposition target. The resultant films exhibit a coexistence of superconductivity and ferromagnetism at 77 K, and a consequent significant enhancement in their absolute critical current density, J(c), compared to pure YBCO films prepared under the same conditions. 'Poisoning' effects due to the incorporation of Fe into the YBCO matrix are avoided at sufficiently low concentrations of inclusions, where the greatest self-field J(c) enhancement is seen, but do become increasingly evident as the concentration is increased. The process outlined has practical application in the synthesis of high-J(c) YBCO films, with the absolute J(c) values obtained in initial samples lying at the upper bound of reported values for samples produced worldwide to date.