Evidence for the Kosterlitz-Thouless Transition in Thin Superconducting Aluminum Films

Abstract

The complex impedance of an aluminum film with normal-state sheet resistance of 4130 \ensuremath{\Omega}/sq has been measured as a function of temperature and frequency. The experiment provides convincing evidence that there is a vortex-antivortex dissociation transition of the type predicted by the theory of Kosterlitz and Thouless for topological long-range order in two dimensions.