AC transverse magnetic field dependence of magnetization in Bi 2Sr 2CaCu 2O 8 single crystal

Abstract

We measured the role of small ac transverse magnetic field on the magnetization of Bi 2Sr 2CaCu 2O 8 single crystal with dc magnetic field along the crystalline c-axis. We observed that the irreversible magnetization diminishes monotonically with increasing ac transverse field, as the dithering of vortices induces easier flux entry and exit into and from the crystal. The frequency dependence showed non-monotonic dependence of the irreversible magnetization with the most reduction near 30 Hz of ac field. We find strong frequency dependence of the irreversible magnetization and the occurrence of flux jumps above the second magnetization peak, that are interpreted in terms of dimensional crossover of vortices from three to two dimension in the peak region with increasing dc magnetic field.