Computer Simulation of Flux Pinning in Type-II Superconductors

Abstract

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: ${j}_{c}=\mathrm{const}\ifmmode\times\else\texttimes\fi{}\frac{{n}_{p}〈{{f}_{p}}^{2}〉}{{R}_{p}{c}_{66}}$ (${j}_{c}$ is the critical current; ${n}_{p}$, ${f}_{p}$, and ${R}_{p}$ are the density, force, and range of pins; and ${c}_{66}$ 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 ${j}_{c}({f}_{p})$ indicates the onset of plastic deformation.