# Power Loss for a Periodically Driven Ferromagnetic Nanoparticle in a Viscous Fluid: the Finite Anisotropy Aspects

## TL;DR

This paper investigates the energy dissipation mechanisms of a ferromagnetic nanoparticle in a viscous fluid under periodic driving, highlighting the influence of magnetic and mechanical dynamics and finite anisotropy effects.

## Contribution

It provides exact expressions for particle trajectories and power loss considering finite anisotropy, comparing different modeling approaches.

## Key findings

- Damping precession dominates energy dissipation in small oscillations.
- Particle easy axis motion significantly affects power loss.
- Finite anisotropy influences the magnetic and mechanical energy exchange.

## Abstract

The joint magnetic and mechanical motion of a ferromagnetic nanoparticle in a viscous fluid is considered within the dynamical approach. The equation based on the total momentum conservation law is used for the description of the mechanical rotation, while the modified Landau-Lifshitz-Gilbert equation is utilized for the description of the internal magnetic dynamics. The exact expressions for the particles trajectories and the power loss are obtained in the linear approximation. The comparison with the results of other widespread approaches, such as the model of fixed particle and the model of frozen magnetic moment, is performed. It is established that in the small oscillations mode the damping precession of the nanopartile magnetic moment is the main channel of energy dissipation, but the motion of the nanoparticle easy axis can significantly influence the value of the resulting power loss.