Flux creep and relaxation phenomena in the presence of weak AC magnetic field

Evolution of the dynamic vortex response during the relaxation process In a superconducting slab situated in parallel DC magnetic field H/sub 0/ and superimposed weak AC field h/sub AC//spl sim/ exp(i/spl omega/t) is studied theoretically for the nonlinear vortex diffusion coefficient corresponding to the vortex liquid state. The phenomenon of "dynamical melting" of the vortex lattice at high induced current levels and its possible manifestation in relaxation characteristics of the dynamic vortex response are discussed. The flux creep rate and the irreversible magnetisation decay are shown to be enhanced by application of weak AC magnetic field h/sub AC/.