Quantifying the complex permittivity and permeability of magnetic nanoparticles

TL;DR

This paper measures the complex permittivity and permeability of superparamagnetic iron-oxide nanoparticles using a waveguide method, providing precise data crucial for biomedical nanoparticle design.

Contribution

It introduces a high-sensitivity measurement technique to accurately quantify the electromagnetic properties of magnetic nanoparticles near ferromagnetic resonance.

Findings

Permeability near FMR aligns with magnetization measurements.

The method offers precise characterization of nanoparticle electromagnetic properties.

Results aid in designing nanoparticles for biomedical applications.

Abstract

The complex permittivity and permeability of superparamagnetic iron-oxide nanoparticles has been quantified using a circular waveguide assembly with a static magnetic field to align the nanoparticle's magnetization. The high sensitivity of the measurement provides the precise resonant feature of nanoparticles. The complex permeability in the vicinity of ferromagnetic resonance (FMR) is in agreement with the nanoparticle's measured magnetization via conventional magnetometry. A rigorous and self-consistent measure of complex permittivities and permeabilities of nanoparticles is crucial to ascertain accurately the dielectric behaviour as well as the frequency response of nanoparticle magnetization, necessary ingredients when designing and optimizing magnetic nanoparticles for biomedical applications.