DEFECTS IN 2-DIMENSIONAL AND 3-DIMENSIONAL SOFT LATTICES - APPLICATION TO VORTICES IN LAYERED SUPERCONDUCTORS

It is shown that within continuum theory and linear elasticity the int eraction of point defects in two-and three-dimensional lattices with i sotropic long-range interaction is ideally screened; i.e., the elastic relaxation of the background lattice exactly compensates the long-ran ge interaction between the defects. A small residual short-range inter action results from the discreteness of the lattice and from the nonli near elastic displacements. The self-energy of a point defect is also strongly reduced by the lattice relaxation. These general results are applied to the lattices of Abrikosov vortex Lines and of point vortice s (''pancakes'') in layered superconductors. In the anisotropic lattic e of pancakes this screening is not complete. In particular, screening changes the sign of the interlayer interaction, and while without scr eening the perpendicular magnetic field of a pancake decreases exponen tially with increasing distance, the screened field decreases only alg ebraically due to the long-range elastic displacements of the pancake lattice around a vacancy or interstitial.