Computer Simulation of Flux Pinning in Type-II Superconductors

Random point pinning of ideal or defective flux-line lattices is simulated on a computer. For weak pins, Larkin and Ovchinnikov's two-dimensional collective pinning is confirmed: jc=const×nₚ〈fₚ²〉Rₚc₆₆ (jc is the critical current; nₚ, fₚ, and Rₚ are the density, force, and range of pins; and c₆₆ is the shear modulus). The constant is determined. Defective lattices are pinned more strongly by factors 1.3 to 3, explaining the observed history effect. A pronounced jump in the curves jc(fₚ) indicates the onset of plastic deformation.