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 measu re 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 temperature s slightly above the KTB transition temperature, the noise is white fo r f < f(xi) and scales as 1/f for f > f(xi). Here f(xi) alpha xi(-z), where xi is the correlation length and z is the dynamic exponent. More over, when all frequencies are scaled by f(xi), data for different tem peratures and frequencies collapse onto a single curve.