We have investigated the vortex motion and the magnetization of high critical temperature superconductors YBa2Cu3O7-d Measurements were made using a vibrating sample magnetometer technique. Several magnetization hysteresis cycles have been obtained for different angles, θ, between the applied magnetic field, H, and the crystallographic c-axis. For T = 30 K we observed a central peak and for T = 80 K we observed a second peak or "fishtail".We have investigated the vortex motion and the magnetization of high critical temperature superconductors YBa2Cu3O7-d Measurements were made using a vibrating sample magnetometer technique. Several magnetization hysteresis cycles have been obtained for different angles, θ, between the applied magnetic field, H, and the crystallographic c-axis. For T = 30 K we observed a central peak and for T = 80 K we observed a second peak or "fishtail"
