PEAK EFFECT IN SUPERCONDUCTORS - MELTING OF LARKIN DOMAINS

Motivated by the recent observations of the peak effect in high-T-c YB CO superconductors, we re-examine the origin of this unusual phenomeno n. We propose that the sharp peak in the critical current as a functio n of temperature or magnetic field is an interesting manifestation of vortex-lattice melting in the presence of weak random pinning. Specifi cally, the rise of the critical current with increasing temperature or field is a result of a crossover from the Larkin pinning length to a length scale set by thermal fluctuations.