Magnetic neutron scattering by magnetic vortices in thin submicron-sized soft ferromagnetic cylinders

TL;DR

This paper derives analytical formulas for magnetic neutron scattering in thin ferromagnetic cylinders with vortex states, enabling detailed analysis of vortex structures from SANS data.

Contribution

It provides the first closed-form algebraic expressions for magnetic SANS cross sections in vortex states of thin cylinders, improving data interpretation.

Findings

Derived analytical SANS cross sections for vortex states

Enabled extraction of vortex displacement details from SANS data

Enhanced understanding of magnetic vortex behavior during magnetization

Abstract

Using analytical expressions for the magnetization textures of thin submicron-sized magnetic cylinders in vortex state, we derive closed-form algebraic expressions for the ensuing small-angle neutron scattering (SANS) cross sections. Specifically, for the perpendicular and parallel scattering geometries, we have computed the magnetic SANS cross sections for the case of small vortex-center displacements without formation of magnetic charges on the side faces of the cylinder. The results represent a significant qualitative and quantitative step forward in SANS-data analysis on isolated magnetic nanoparticle systems, which are commonly assumed to be homogeneously or stepwise-homogeneously magnetized. We suggest a way to extract the fine details of the magnetic vortex structure during the magnetization process from the SANS measurements in order to help resolving the long standing question of the magnetic vortex displacement mode.