Regime interpretation of anomalous vortex dynamics in 2D superconductors

Abstract

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 μ_V(ω)~σ₁⁻¹, and is in conflict with general dynamical scaling expressions. We calculate (a) σ(ω,T) by real-space vortex scaling and (b) μ_V(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).