Pinning Property of Nd-Ba-Cu-O Superconductors

The effects of the second phase (Nd4Ba2Cu2Ox; Nd422) on the pinning property of Nd-Ba-Cu-O crystals have been studied. Hysteresis loops and magnetic relaxation were measured with a SQUID magnetometer. Critical current density (J s ) is obtained from the hysteresis loops using extended Bean model. The normalized relaxation rate (S) and the apparent pinning energy (U*0) are deduced from the relaxation data using Anderson-Kim model. It was found that J c -B curves and U*0-B curves are strongly dependent on the volume fraction of Nd422 phase, like Y211 phase with Y-Ba-Cu-O system.