Acoustic-domain resonance mode in magnetic closure-domain structures: A probe for domain-shape characteristics and domain-wall transformations

Abstract

The magnetic-domain resonance was studied for varying closure-domain structures in Co 40 Fe 40 B 20 thin-film elements. A domain-shape anisotropy model was introduced, by which a significant increase of the acousticdomain resonance frequency for decreasing domain width is predicted. We show that magnetic flux closure further increases the domain-width effect on the acoustic-domain resonance frequency. Furthermore, the domain resonance frequency is very sensitive to the effective width of the magnetic-domain walls due to dynamic dipolar interaction. The latter is quantified by calculating the dynamic wall width dependent dipolar fields. Domain-wall transitions in external magnetic fields manifest in either smooth or sudden resonance frequency changes, depending on the involved domain-wall types. Quantitative agreement between experimental and modeled data is obtained. Measuring the acoustic-domain resonance in small excitation fields therefore displays a method to analyze domain-wall instabilities and domain-wall interactions.

Ferromagnetic resonance in Mn5Ge3 epitaxial films with weak stripe domain structure

“…The dynamic response to high frequency magnetic excitations of such low-Q magnetic thin films has been studied by FMR in hexagonal Co [19,20], FePd [18,21], Co 2 MnGa [12] and by zerofield microwave susceptibility in several magnetic alloys, e.g. CoNbZr [22], CoFeZr [23], CoFeB [24] CoZrTa [25], and permalloy [26].…”

Magnetic domain walls as broadband spin wave and elastic magnetisation wave emitters

“…Saturation polarisation of the ferromagnetic material is J s = 1.5 T . An induced uniaxial magnetic anisotropy of K u = 1300 J / m 3 is introduced by applying a magnetic field of H d ep = 8 kA / m during magnetic layer deposition 30 . The saturation magnetostriction is λ s ≈ 25 × 10 −6 34 .…”

“…The narrow domain width leads to different effective fields as compared to Fig. 1(b), giving rise to a higher domain resonance frequency 29,30 of ω/2π = 2.5 GHz. From the time evolution of ∆m y , it is directly apparent that the periodicity of the elastic waves shifted to smaller wavelengths.…”