Physical aging and rejuvenation in the vortex matter of superconducting Nb50Zr50

Abstract

We report the experimental evidence of physical aging and rejuvenation in the vortex matter of a conventional low-T C superconducting Nb50Zr50 alloy. The underlying naturally formed microstructure indicates a landscape of pinning potential for the flux lines, on the basis of which the pinning properties are explained. Magnetic relaxation measurements were used to construct the two-time auto correlation function which is a function of the measuring time ‘t’ and waiting time ‘t w ’ after the vortex state is prepared. The main characteristic features of the phenomenon of physical aging, which are the breaking of time-translation invariance and dynamical scaling are seen. Successive aging of the vortex matter after following different histories in the (H, T) phase space is non-cumulative in nature, which is also known as the phenomena of rejuvenation. These experimental observations of relaxation dynamics along with the features of microstructure of our sample seem to agree with the theoretical models of aging phenomenon in a system of elastic lines pinned by random quenched disorder that leads to hierarchical modes of relaxation.