Ferromagnetic resonance of coupled shifted chains of nano-elements

TL;DR

This paper studies the ferromagnetic resonance of coupled chains of iron nanoparticles, considering finite size effects and shape, revealing a critical magnetic field value indicating a state transition relevant for magnetic recording.

Contribution

It introduces a detailed model of FMR in coupled nano-chains that accounts for finite size and shape, extending beyond point-dipole approximations.

Findings

Resonance frequency depends on applied field amplitude.

Resonance field varies with field direction in different planes.

Identification of a critical magnetic field for state transition.

Abstract

We investigate the FMR characteristics of a magnetic dimer composed of two chains of iron nanoparticles coupled by dipolar interactions. The latter are treated beyond the point-dipole approximation taking into account the finite size and arbitrary shape of the nano-elements. The resonance frequency is calculated as a function of the amplitude of the applied magnetic field and the resonance field is computed as a function of the direction of the applied field, varied both in the plane of the two chains and perpendicular to it. We highlight a critical value of the magnetic field which marks a state transition that should be important in magnetic recording media.