Thermo-magnetic history effects in the vortex state of YNi₂B₂C superconductor

Abstract

The nature of five-quadrant magnetic isotherms for H||a is different from that for H||c in a single crystal of YNi₂B₂C, pointing towards an anisotropic behaviour of the flux line lattice (FLL). For H||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||c, the loop is closed and one can observe only the PE. We have investigated the history dependence of magnetization hysteresis data for H||a by recording minor hysteresis loops. The observed history dependence in J_C(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.