The effect of stripe domain structure on dynamic permeability of thin ferromagnetic films with out-of-plane uniaxial anisotropy

TL;DR

This paper derives analytical expressions for the frequency-dependent permeability of thin ferromagnetic films with stripe domains and out-of-plane anisotropy, aiding the development of high-permeability microwave magnetic materials.

Contribution

It introduces a theoretical model for permeability in stripe domain ferromagnetic films considering anisotropy and domain structure effects.

Findings

Derived analytical expressions for permeability tensor components.

Identified conditions for maximal microwave permeability.

Analyzed the influence of domain width and anisotropy angle.

Abstract

The permeability is calculated for a thin ferromagnetic film with the stripe domain structure and out-of-plane uniaxial magnetic anisotropy. Analytical expressions for the frequency dependence of components of permeability tensor are derived with the use of the Smit-Beljers method, with the thickness of domain walls and the domain wall motion being neglected. The effect of the domain width and the angle between the anisotropy axis and the film plane on the frequency dependence of the permeability is analyzed. General equations relating the static permeability components and the ferromagnetic resonance frequencies are found. The results of the approach are applied to the derivation of the constraint for the microwave permeability of thin ferromagnetic films. The analysis of the constraint as a function of the axis deviation angle, the domain aspect ratio and the damping parameter allows the conditions to be found for maximal microwave permeability. The results obtained may be useful in connection with the problem of developing high-permeable microwave magnetic materials.