Anomalous vortex dynamics in 2D superconductors

TL;DR

This paper investigates anomalous vortex dynamics in 2D superconductors, revealing a new intermediate-frequency scaling regime that explains experimental observations and differs from traditional dynamical scaling predictions.

Contribution

The study introduces a novel intermediate-frequency scaling regime for vortex conductivity, reconciling experimental data with theoretical models in 2D superconductors.

Findings

Identification of a new intermediate-frequency scaling regime

Experimental data fall into the predicted scaling regime

Resolution of conflict with traditional dynamical scaling expressions

Abstract

Low -frequency dynamic impedance ($\sigma^{-1}(\omega,T)\equiv(\sigma_{1}+i\sigma_{2})^{-1}$) measurements on Josephson junction arrays with finite vortex screening length $\xi$, found that $\sigma_{1}\sim |\log{\omega}|$, $\sigma_{2}\sim$ constant. This implies anomalously sluggish vortex mobilities $\mu_{V}(\omega)\sim\sigma_{1}^{-1}$, and is in conflict with general dynamical scaling expressions that yield, for low-$\omega$, $\sigma_{1}\rightarrow\xi^{2}$ and $\sigma_{2}\rightarrow 0$. We calculate : a) $\sigma(\omega,T)$ by real-space vortex scaling; b) $\mu_{V}(\omega)$ using Mori's formalism for a screened Coulomb gas. We find, in addition to the usual critical (large-$\omega$) and hydrodynamic (low-$\omega$) 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 $\sigma(\omega,T)$, testable in SNS and SIS arrays.