Vibrating Sample Magnetometry of High-Tc Superconductor Y-Ba-Cu Oxide

Magnetic properties of a high-T c superconductor Y-Ba-Cu oxide are studied by using a vibrating sample magnetometer. The specimen prepared shows a rapid resistivity drop at 95 K and zero-resistance state at 91 K. A diamagnetic susceptibility as large as 43% of the perfect diamagnetism is observed at a temperature as high as 84 K. At this temperature, the lower critical field is about 200 Oe and the upper critical field is suggested to be higher than 10 T.