Low-frequency dynamic impedance [σ−1(ω,T)≡(σ1+iσ2)−1] measurements on Josephson junction arrays found that σ1∼|lnω|, σ2∼const. This implies anomalously sluggish vortex mobilities μV(ω)∼σ−11, and is in conflict with general dynamical scaling expressions. We calculate (a) σ(ω,T) by real-space vortex scaling and (b) μV(ω) using Mori's formalism for a screened Coulomb gas. We find, in addition to the usual critical (large-ω) and hydrodynamic (low-ω) regimes, a new intermediate-frequency scaling regime into which the experimental data fall. This resolves the above mentioned conflict and makes explicit predictions for the scaling form of σ(ω,T).
Henrik Moodysson Rønnow, Ivica Zivkovic, Richard Gaal, Youngro Lee