PEAK EFFECT IN SUPERCONDUCTORS: ABSENCE OF PHASE TRANSITION AND POSSIBILITY OF JAMMING IN VORTEX MATTER

Abstract

The magnetic field B dependence of the critical current Ic for the vortex phase of a disordered superconductor is studied numerically at zero temperature. The Ic(B) increases rapidly near the upper critical field Bc2 similar to the peak effect (PE) phenomenon observed in many superconductors. The real space configuration across the PE changes continuously from a partially ordered domain (polycrystalline) state into an amorphous state. For B≥0.4Bc2, the topological defect density nd(b) increases as eαBk with k>1. There is no evidence of a phase transition in the vicinity of the PE suggesting that an order-disorder transition is not essential for the occurrence of the PE phenomenon. An alternative view is presented wherein the vortex system with high dislocation density undergoes jamming at the onset of the PE.