A Structural Optimization of Ferrite/YBCO Bilayers
Magnetic particles can be used to take advantage of both defect and magnetic pinning in high-temperature superconductors. We combined layers of ferrite+cerium oxide with YBCO to see their effect both on the structure of the YBCO and on flux pinning. The deposition temperature of the ferrite greatly affects its structure and also the saturation magnetization. Combined with YBCO, the magnetic layer distorts the structure of YBCO, although, for example, the critical temperature remains rather unchanged. According to the structural results achieved here, the magnetic pinning layer is best positioned on the top of YBCO. This way, an improvement in Jc(B) is seen in all the field range, and also, a clear improvement of the accommodation field was measured. However, it does not play a huge role whether the ferrite is CoFe2O4, NiFe2O4, or ZnFe2O4, all mixed with CeO2.