Magnetic behavior of both superconducting thin films and their deposition targets

The superconducting properties of the bulk oxides La/sub 1.85/Sr/sub 0.15/CuO/sub 4-//sub x/ and Ba2YCu3O/sub 7-//sub y/ were investigated through their magnetic behavior by vibrating-sample magnetometry and complex ac susceptibility, and by dc resistivity and microwave response. These oxides were then used as targets in the preparation of thin films using a laser-ablation technique. The superconducting properties of the films were established through their microwave response. The M-H loops at low temperatures clearly establish the type-II behavior of the Ba-Y-Cu-O materials. The real part of the ac susceptibility showed the superconducting transition. Simultaneously, the imaginary part of the ac susceptibility showed the existence of nonsuperconducting portions in the samples which have a low enough resistivity to carry a significant amount of current. The novel method of microwave response was used to detect the superconductivity for both the bulk oxides and the thin films