Vortex Washboard Voltage Noise in Type-II Superconductors

TL;DR

This study uses Monte Carlo simulations to analyze how different types of defects affect vortex behavior and voltage noise in disordered type-II superconductors, revealing defect-dependent features in vortex structure and noise spectra.

Contribution

It provides new insights into the influence of columnar and point defects on vortex dynamics and voltage noise, highlighting the role of defect strength and type in vortex transport properties.

Findings

Washboard noise peak intensity ratios depend on defect strength, not type.

Vortex radius of gyration exhibits unique defect-dependent features.

Material defects significantly influence vortex transport and noise characteristics.

Abstract

In order to characterize flux flow through disordered type-II superconductors, we investigate the effects of columnar and point defects on the vortex velocity / voltage power spectrum in the driven non-equilibrium steady state. We employ three-dimensional Metropolis Monte Carlo simulations to measure relevant physical observables including the force-velocity / current-voltage (I-V) characteristics, vortex spatial arrangement and structure factor, and mean flux line radius of gyration. Our simulation results compare well to earlier findings and physical intuition. We focus specifically on the voltage noise power spectra in conjunction with the vortex structure factor in the presence of weak columnar and point pinning centers. We investigate the vortex washboard noise peak and associated higher harmonics, and show that the intensity ratios of the washboard harmonics are determined by the strength of the material defects rather than the type of pins present. Through varying columnar defect lengths and pinning strengths as well as magnetic flux density we further explore the effect of the material defects on vortex transport. It is demonstrated that the radius of gyration displays quantitatively unique features that depend characteristically on the type of material defects present in the sample.