Magnetization Reversal in Elongated Fe Nanoparticles

TL;DR

This study investigates how individual elongated Fe nanoparticles reverse their magnetization, revealing size-dependent mechanisms involving thermal activation and inhomogeneous magnetic structures.

Contribution

It provides new insights into the magnetization reversal processes in high-aspect-ratio Fe nanoparticles at the nanoscale.

Findings

5 nm particles reverse magnetization via incoherent nucleation

Larger particles exhibit reversal influenced by inhomogeneous magnetic structures

Thermal activation assists localized nucleation during reversal

Abstract

Magnetization reversal of individual, isolated high-aspect-ratio Fe nanoparticles with diameters comparable to the magnetic exchange length is studied by high-sensitivity submicron Hall magnetometry. For a Fe nanoparticle with diameter of 5 nm, the magnetization reversal is found to be an incoherent process with localized nucleation assisted by thermal activation, even though the particle has a single-domain static state. For a larger elongated Fe nanoparticle with a diameter greater than 10 nm, the inhomogeneous magnetic structure of the particle plays important role in the reversal process.