1/\omega-flux-noise and dynamical critical properties of two-dimensional XY-models

TL;DR

This study numerically investigates the dynamic correlation functions and flux noise in two-dimensional XY-models with different dissipation mechanisms, revealing temperature-dependent noise spectra and critical exponents, and highlighting vortex cluster diffusion effects.

Contribution

It provides new insights into flux noise behavior and dynamic critical properties of 2D XY-models with bond and site dissipation, aligning TDGL results more closely with experimental data.

Findings

Flux noise spectra follow a power-law form with temperature-dependent exponents.

Dynamic critical exponents differ for TDGL and RSJ models, with TDGL closer to experiments.

Vortex cluster diffusion influences anomalous flux noise and critical dynamics.

Abstract

We have numerically studied the dynamic correlation functions in thermodynamic equilibrium of two-dimensional O(2)-symmetry models with either bond (RSJ) or site (TDGL) dissipation as a function of temperature T. We find that above the critical temperature the frequency dependent flux noise $S_{\Phi}(\omega)\sim \vert 1+ {(\omega/\Omega)}^2\vert^{-\alpha (T)/2}$, with $0.85\leq \alpha (TDGL)(T)\leq 0.95$ and $1.17 \leq \alpha (RSJ)(T) \leq 1.27$, while the dynamic critical exponents $z(TDGL)\sim 2.0$ and $z(RSJ)\sim 0.9$. Contrary to expectation the TDGL results are in closer agreement with the experiments in Josephson-junction arrays by Shaw et al., than those from the RSJ model. We find that these results are related to anomalous vortex diffusion through vortex clusters.