Motion of current-driven vortex solids with weak pinning in the Corbino disk

Abstract

We report on the dynamic response of a weakly disordered vortex lattice driven by a radial current I in an amorphous MoxGe1−x film with a Corbino-disk (CD) geometry. In CD, the vortices circulate around the center of the sample by feeling a nonuniform Lorentz force inversely proportional to the radius of rotation. We observe the peak in the dynamic critical current, as well as, in the static critical current, as a function of the magnetic field. This means that, even when the vortices are in circular motion, they feel the maximum pinning force just prior to ‘dynamic’ melting. As I is increased in the solid state, the vortices near the center are first depinned and then exhibit the plastic-flow-like rotation. This is in contrast to previous work for a YBa2Cu3O7−δ single-crystal, in which the elastic rotation is observed.