Magnetic Properties of FeNi/Cu-Based Lithographic Rectangular Multilayered Elements for Magnetoimpedance Applications

Abstract

The rectangular elements in magnetoimpedance (MI) configuration with a specific nanocomposite laminated structure based on FeNi and Cu layers were prepared by lift-off lithographic process. The properties of such elements are controlled by their shape, the anisotropy induced during the deposition, and by effects associated with the composite structure. The characterizations of static and dynamic properties, including MI measurements, show that these elements are promising for sensor applications. We have shown that competition between the shape anisotropy and the in-plane induced anisotropy of the element material is worth taking into account in order to understand the magnetic behavior of multilayered rectangular stripes. A possibility of the dynamic methods (ferromagnetic and spin-wave resonance) to describe laminated planar elements having a non-periodic modulation of both structure and magnetic parameters of a system is demonstrated. We show that the multilayered structure, which was originally designed to prevent the development of a “transcritical” state in magnetic layers and to reach the required thickness, also induces the effects that hinder the achievement of the goal, namely an increase in the perpendicular magnetic anisotropy energy.

Competing Magnetocrystalline and Shape Anisotropy in Thin Nanoparticles

“…The size of the defined nanoparticles corresponds to those found in the existing literature [46], but is also close to the magnetic inclusions in minerals [6]. The thickness of the cylinders was selected to be much lower than hundreds of nms to avoid the formation of stripe domains, whose origins involve quite different mechanisms [8,9,11]. The results indicate to what extent the nanoparticles under study can be treated as macrospins.…”

“…In systems close to a circular shape, a vortex or a number of vortices occur with a core/cores where the magnetic moment is directed perpendicular to the particle's plane. The reason for this out-of-plane magnetisation is not related to a perpendicular magnetic anisotropy, as is the case in the stripe domains [8]. As the magnetic field is always parallel to one of the semiaxes of the ellipse, the formation of vortices is an instance of spontaneous symmetry breaking.…”

“…The reasons for this effect are in fact multiple, e.g., competition between the shape anisotropy and the in-plane induced anisotropy of the underlying and/or intercalating material [8], magnetostriction and external stress [9] effects of the thin-film growth mechanisms [10], and columnar microstructure [11]. It should be noted, however, that, as remarked by the authors of [8,12], the stripe domains appear at thicknesses on the order of hundreds of nanometres.…”

“…If the thickness exceeds a critical value defined by the in-plane shape as well as by the magnetocrystalline anisotropy of the constituent material, a perpendicular magnetic anisotropy (PMA) may arise along with an out-of-plane magnetisation component whose interplay with the in-plane properties may give rise to stripe domains [7]. The reasons for this effect are in fact multiple, e.g., competition between the shape anisotropy and the in-plane induced anisotropy of the underlying and/or intercalating material [8], magnetostriction and external stress [9] effects of the thin-film growth mechanisms [10], and columnar microstructure [11]. It should be noted, however, that, as remarked by the authors of [8,12], the stripe domains appear at thicknesses on the order of hundreds of nanometres.…”

Magnetic Properties of Amorphous Ta/CoFeB/MgO/Ta Thin Films on Deformable Substrates with Magnetic Field Angle and Tensile Strain

“…Additionally, the dominant effect of the interfaces of the thin films influences their properties. Studies have used these properties to assess the magnetic anisotropy characteristics such as perpendicular magnetic anisotropy (PMA) [17][18][19], which normally needs to be very thin thickness, and in-plane magnetic anisotropy (IMA), which occurs in relatively thick films [16,20]. Currently, several research groups aim to understand the alterations in these properties to fulfill a long-term goal of implementing these changes along with the basic magnetic properties of thin films in various applications.…”