Possibility of Vortex-Antivortex Pair Dissociation in Two-Dimensional Superconductors

The possible existence of a Kosterlitz-Thouless vortex-antivortex dissociation transition in thin superconducting films is discussed. It is found that in practice the situation should be closely analogous to that predicted for superfluid-helium films. A simple relationship is found between the Kosterlitz-Thouless transition temperature and the sheet resistance. This relationship is compared with the observed broadening of the resistive transition of superconducting films with high sheet resistance.