Micromagnetic modelling of anisotropic damping in ferromagnet

TL;DR

This paper introduces a numerical implementation of anisotropic damping in micromagnetic simulations based on the Landau-Lifshitz-Baryakhtar theory, revealing how tensor symmetry influences magnonic linewidths in ferromagnetic structures.

Contribution

It presents a novel tensor-based damping model in micromagnetics and explores its effects on magnonic resonance linewidths in ferromagnetic disks and ellipses.

Findings

Linewidth anisotropy depends on the relaxation tensor projection and precession ellipticity.

Simulation results match experimental trends of anisotropic damping effects.

Tensor symmetry significantly influences magnetic relaxation behavior.

Abstract

We report a numerical implementation of the Landau-Lifshitz-Baryakhtar theory, which dictates that the micromagnetic relaxation term obeys the symmetry of the magnetic crystal, i. e. replacing the single intrinsic damping constant with a tensor of corresponding symmetry. The effect of anisotropic relaxation is studied in thin saturated ferromagnetic disk and ellipse with and without uniaxial magneto-crystalline anisotropy. We investigate the angular dependency of the linewidth of magnonic resonances with respect to the given structure of the relaxation tensor. The simulations suggest that the anisotropy of the magnonic linewidth is determined by only two factors: the projection of the relaxation tensor onto the plane of precession and the ellipticity of the later.