A versatile simulation of slow moving vortex lattices

TL;DR

This paper presents a versatile simulation software for modeling slow vortex lattice dynamics, reproducing observed patterns and exploring defect effects in superconductors, based on detailed vortex interactions and boundary conditions.

Contribution

The paper introduces a comprehensive simulation tool that accurately models vortex-vortex and vortex-defect interactions, enabling detailed analysis of vortex behavior in superconductors.

Findings

Simulation reproduces experimental vortex track patterns.

Vortex velocity and lattice distortions are affected by defect configurations.

Global time step control improves simulation stability.

Abstract

We designed and implemented our own versatile simulation software in order to understand the velocity changes and track patterns observed in slow moving vortex lattices. The data was obtained from time series of STM images on NbSe$_2$ in a magnetic field range of 250-750 mT. The main thrust is to explore possible driving mechanism and to test the effect of various defect configuration on vortex velocity and tracks. The simulation uses the full vortex--vortex and vortex--defect interaction. It allows for periodic boundary conditions as well as a repulsive sample edge. In early versions the time intervals for recalculating the force were estimated for individual vortices. This, however, led to a positional 'noise' of unacceptable temperature of the vortex lattice and was hence replaced by a global time step control. We were able to produce similar track and velocity patterns as well as local lattice distortions near point defects as observed by STM. A detailed analysis is, however, beyond the scope of this paper.