VORTEX-ANTIVORTEX INTERACTION IN HIGH-T-C SUPERCONDUCTORS

The free energy of a vortex-antivortex pair in a Josephson-coupled lay ered superconductor is derived within the framework of the Lawrence-Do niach theory. We find that the free energy. of large pairs depends Lin early on the pair separation and that there is no logarithmic term in the free energy for large pairs. We also derive the free energy of a p air of vortex lines, i.e., a vortex-antivortex pair in every layer. It is found that the free energy of this system corresponds to the usual result for conventional superconductors. In conclusion we discuss tha t the vortex-antivortex interaction cannot be described by a simple mo dification of the Kosterlitz-Thouless theory.