Renormalized interactions and dissociation of vortices in layered superconductors

In layered superconductors, thermal fluctuations excite vortex-antivortex pairs within the layers and thereby renormalize the interactions of the vortices. This leads to a modification of the temperatures, at which vortex-antivortex pairs and single flux lines dissociate. We calculate the renormalized interactions in a self-consistent linear response approach. As a direct consequence of flux quantization, vortex-antivortex pairs and flux lines dissociate at the same temperature. We derive the fugacity-versus-temperature phase diagram of the dissociation process for vanishing external magnetic field. An analysis of the phase diagram with experimental data of Bi-type high-Tc superconductors reveals that the renormalization significantly affects the determination of the magnetic penetration depth from resistivity measurements.