Charge Kosterlitz-Thouless Transition in Two-Dimensional Arrays of Small Tunnel Junctions

Abstract
We observed temperature dependence of resistance in two-dimensional random and regular small tunnel junction arrays, in the normal and superconducting states. Precursor behaviors of the charge Kosterlitz-Thouless (K-T) transitions were observed for the first time. We also observed the vortex K-T transition in random arrays. The results are consistent with theoretical phase diagrams.