Thermo-magnetic history effects in the vortex state of YNi(2)B(2)C superconductor

Abstract

The nature of five-quadrant magnetic isotherms for H parallel to a is different from that for H parallel to c in a single crystal of YNi(2)B(2)C, pointing towards an anisotropic behaviour of the flux line lattice (FLL). For H parallel to a, a well defined peak effect (PE) and second magnetization peak (SMP) can be observed and the loop is open prior to the PE. However, for H parallel to c, the loop is closed and one can observe only the PE. We have investigated the history dependence of magnetization hysteresis data for H parallel to aby recording minor hysteresis loops. The observed history dependence Jc(H) across different anomalous regions are rationalized on the basis of superheating/supercooling of the vortex matter across the first-order-like phase transition and possible additional effects due to annealing of the disordered vortex bundles to the underlying equilibrium state.