Theory of Plastic Vortex Creep

Abstract

We develop a theory for plastic vortex creep in a topologically disordered (dislocated) vortex solid phase in type-II superconductors in terms of driven thermally activated dislocation dynamics. Plastic barriers for dislocations show a power-law divergence at small driving currents $j$, ${U}_{\mathrm{pl}}(j)\ensuremath{\propto}{j}^{\ensuremath{-}\ensuremath{\mu}}$, with $\ensuremath{\mu}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$ for a single dislocation and $\ensuremath{\mu}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2/5$ for creep of dislocation bundles. This implies a suppression of the creep rate at the transition from the ordered vortex phase ( $\ensuremath{\mu}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2/11$) to the dislocated glass and can manifest itself as an observed increase of the apparent critical current (second peak). Our approach applies to general dynamics of disordered elastic media on a random substrate.