PEAK EFFECT AND THE TRANSITION FROM ELASTIC TO PLASTIC DEPINNING

We demonstrate for the first time an observation of the peak effect in simulations of magnetic vortices in a superconductor. The shear modul us c(66) of the vortex lattice is tuned by adding a fictitious attract ive short-range potential to the usual long-range repulsion between vo rtices. The peak effect is found to be most pronounced in low densitie s of pinning centers, and is always associated with a transition from elastic to plastic depinning. The simulations suggest in some situatio ns that over a range of values of c(66) the production of lattice defe cts by a driving force enhances the pinning of the lattice.