Magnetization dynamics in nanostructures with weak/strong anisotropy

Abstract

We investigate the high-frequency response of magnetization dynamics through magnetoimpedance (MI) effect in Permalloy-based multilayered thin films produced with two different non-magnetic metallic spacers: Cu and Ag. Due to the nature of the spacer materials, we are able to play with magnetic properties and to study both systems with weak/strong magnetic anisotropy. We verify very rich features in the magnetoimpedance behavior and high magnetoimpedance ratios, with values above 200%. We compare the MI results obtained in multilayered thin films with distinct spacers and number of bilayers, and discuss them in terms of the different mechanisms that govern the MI changes observed at distinct frequency ranges, intensity of the magnetic anisotropy, alignment between dc magnetic field and anisotropy direction. Besides, by considering a theoretical approach that takes into account two single models together and calculate the transverse magnetic permeability and the MI effect, we support our interpretation via numerical calculations modeling the effect of weak/strong magnetic anisotropy on the MI response. Thus, we confirm that these features are very important for the use of multilayered films in sensor applications and, both the frequency and field response can be tailored to fulfill the requirements of a given device.

Asymmetric magnetoimpedance effect in ferromagnetic multilayered biphase films

“…By considering the curves acquired with the magnetic field along the main axis, the higher hysteretic losses verfied with the raise of n are consistent with the stress stored in the film, roughness of the interfaces and lack of homogeneity of the Cu layer arisen as the total thickness of the sample increases [13,14], as well as related to orange peel and similar effects.…”

Quantifying magnetic anisotropy dispersion: Theoretical and experimental study of the magnetic properties of anisotropic FeCuNbSiB ferromagnetic films

“…On the other hand, just a few studies compare numerical calculations and experimental results, probably due to the fact that the determination of the appropriate magnetic free energy density can represent a hard task. In particular, some successful examples reside in the employment of the anisotropic SW model to study the influence of the magnetic anisotropy on the properties of sintered magnets composed by SmCo 5 and Co [20,21], to describe transverse susceptibility of FeCoV thin films [25], and to investigate the magnetoimpedance effect in ferromagnetic films [42][43][44].…”

Magnetoimpedance effect at the high frequency range for the thin film geometry: Numerical calculation and experiment

“…However, nowadays, similar information can be accessibly obtained also through the study of the magnetoimpedance effect. This effect is a versatile tool commonly employed to investigate ferromagnetic materials, revealing aspects on the fundamental physics associated to magnetization dynamics, broadband magnetic properties [1][2][3] , as well as on important issues for current and emerging technological applications for magnetic sensors [4][5][6][7][8] . Besides, further insights on FMR effect at non-saturated magnetic states of the sample can be easily gotten, making possible the study of local resonances and their influence in the dynamics magnetization.…”