Magnetic hyperthermia in single-domain monodisperse FeCo nanoparticles: Evidences for Stoner-Wohlfarth behaviour and large losses

TL;DR

This study investigates the magnetic hyperthermia properties of 15 nm monodisperse FeCo nanoparticles, demonstrating Stoner-Wohlfarth behavior and high energy losses suitable for medical applications.

Contribution

It provides experimental evidence of single-domain ferromagnetic behavior and quantifies hyperthermia losses in FeCo nanoparticles, aligning with a simple non-interacting particle model.

Findings

Losses reach 1.5 mJ/g, among the highest reported.

Losses exhibit a sharp increase and plateau with magnetic field.

Frequency dependence of coercive field matches model predictions.

Abstract

We report on hyperthermia measurements on a colloidal solution of 15 nm monodisperse FeCo nanoparticles (NPs). Losses as a function of the magnetic field display a sharp increase followed by a plateau, which is what is expected for losses of ferromagnetic single-domain NPs. The frequency dependence of the coercive field is deduced from hyperthermia measurement and is in quantitative agreement with a simple model of non-interacting NPs. The measured losses (1.5 mJ/g) compare to the highest of the literature, though the saturation magnetization of the NPs is well below the bulk one.