Vacancy and interstitial defects in the vortex lattice of superconducting thin films

Abstract

A method developed previously for the lattice of infinitely long parallel Abrikosov vortices in type-II superconductors is extended to vortices in thin superconducting films. The self-energy and interaction energy of vacancies and interstitials in the triangular lattice of vortices in the film are calculated within London theory. Various stable and metastable equilibrium configurations of the flux-line lattice around such point defects are found, similar to the result for long vortex lines. In particular, the vacancy with highest (sixfold) symmetry usually does not exhibit the lowest energy, and the defect energies are very small compared with the binding energy of one vortex due to the relaxation of the surrounding vortex lattice. The interaction between point defects is weak, but is attractive as opposed to the long parallel Abrikosov vortex case where the defect interaction can be repulsive in some cases. © 1999 American Physical Society.