Dynamic Scaling of Magnetic Flux Noise near the Kosterlitz-Thouless-Berezinskii Transition in Overdamped Josephson Junction Arrays

We have used a dc superconducting quantum interference device to measure the magnetic flux noise generated by the equilibrium vortex density fluctuations associated with the Kosterlitz-Thouless-Berezinskii (KTB) transition in an overdamped Josephson junction array. At temperatures slightly above the KTB transition temperature, the noise is white for f<f_ξ and scales as $1/f$ for f>f_ξ. Here f_ξ∝ξ^-z, where ξ is the correlation length and z is the dynamic exponent. Moreover, when all frequencies are scaled by f_ξ, data for different temperatures and frequencies collapse onto a single curve.