Renormalization Effects of Vortex-Antivortex Pairs in Layered Superconductors

The interactions of point vortices in electromagnetically coupled superconducting layers are renormalized by thermally excited vortex-antivortex pairs. We calculate these renormalized interactions in a self-consistent linear-response theory. Thereby we derive the renormalized dissociation temperatures of vortex-antivortex pairs and of single flux lines. It has been noted previously that both temperatures are equal in the absence of thermally created vortex-antivortex pairs. We find the equality even in the renormalized theory and prove it as a direct consequence of flux quantization. Finally we derive the phase diagram of the layered system for zero external field and apply it to experimental data for Bi-type high- T c superconductors.