Non-reciprocal light diffraction by a vortex magnetic particle

TL;DR

This paper presents a theoretical analysis of non-reciprocal light diffraction caused by vortex magnetization in spherical magnetic particles, highlighting the role of electric quadrupole and magnetic dipole excitations.

Contribution

It introduces a theoretical model explaining non-reciprocal diffraction effects in magnetic particles with vortex magnetization, aligning with recent experimental observations.

Findings

Non-reciprocal diffraction depends on magnetization vorticity.

Electric quadrupole and magnetic dipole excitations are responsible.

Estimated effects match experimental data within an order of magnitude.

Abstract

We report a theoretical study of light diffraction by a spherical magnetic particle with a vortex magnetization distribution. It is shown that the intensity of the diffracted light involves a non-reciprocal contribution. This contribution depends on the vorticity of particle magnetization. It appears due to the excitation of an electric quadrupole, magnetic dipole and the addition to the electric dipole moment in the particle, that depend on the particle magnetization vorticity. The estimation of the non-reciprocal contrbution for a cobalt particle and two linear polarizations of the incident light fits the data of recent experimental studies in the lattice of triangle magnetic particles by an order of magnitude.