Time-dependent Ginzburg-Landau treatment of RF Magnetic Vortices in Superconductors: Vortex-Semiloops in a Spatially Nonuniform Magnetic Field

TL;DR

This paper uses time-dependent Ginzburg-Landau simulations to analyze vortex semiloops in superconductors under non-uniform RF magnetic fields, revealing vortex dynamics and nonlinear responses.

Contribution

It introduces a novel two-domain simulation approach to model inhomogeneous magnetic fields and vortex behavior in superconductors, advancing understanding of their RF response.

Findings

Vortex semiloops penetrate deep into the superconductor.

Nonlinear third-harmonic response is characterized.

Defects influence vortex dynamics and semi-loop behavior.

Abstract

We apply time-dependent Ginzburg Landau (TDGL) numerical simulations to study the finite frequency electrodynamics of superconductors subjected to intense rf magnetic field. Much recent TDGL work has focused on spatially uniform external magnetic field and largely ignores the Meissner state screening response of the superconductor. In this work, we solve the TGDL equations for a spatially non-uniform magnetic field created by a point magnetic dipole in the vicinity of a semi-infinite superconductor. A novel two-domain simulation is performed to accurately capture the effect of the inhomogeneous applied fields and the resulting screening currents. The creation and dynamics of vortex semiloops penetrating deep into the superconductor domain is observed and studied, and the resulting third-harmonic nonlinear response of the sample is calculated. The effect of point-like defects on vortex semi-loop behaviour is also studied. This simulation method will assist our understanding of the limits of superconducting response to intense rf magnetic fields.