Formation Of Magnetic Anisotropy Research Articles

Electric field control of magnetization reversal in FeGa/PMN-PT thin films

Abstract Artificial magnetoelectric materials possess huge potential to be utilized in the development of energy efficient spintronic devices. In the past decade, the search for a good ferromagnetic/ferroelectric combination having the ability to create high magnetoelectric coupling, created new insights and also new challenges. In this report, the magnetoelectric effect is studied in the FeGa/PMN-PT(001) multiferroic heterostructures in the presence of electric fields via strain-mediated effects. The formation of magnetic anisotropy in FeGa is observed after changing the polarization of PMN-PT to out-of-plane orientations. The magnetic domain structures forming during the magnetization reversal were studied in compressive, tensile and remanent strained states. The changes in the magnetic properties were reversible after each cycling of the electric field polarity, hence creating a non-volatile system. The control of magnetization switching sustained by an ON–OFF electric field makes our multiferroic heterostructure suitable for application in low-power magnetoelectric based memory applications.

Magneto-impedance tomography of CoFeTaSiB amorphous wires

The paper presents the results of a study of the radial distribution of the magnetic permeability of an Co66Fe4Ta2.5Si12.5B15 amorphous wire with a radius of 55 μm. The study was performed using magneto-impedance tomography in the frequency range of alternating current from 0.01 to 100 MHz. It was found that the magnetic permeability significantly depends on the radial coordinate. Wherein the inner regions of the wire have predominantly axial anisotropy, while the outer layer about 2.5 µm thick has circular anisotropy. It is shown that the magnetoelastic mechanism is not the main one in the formation of magnetic anisotropy in the surface layer of the wire.

Formation of magnetic anisotropy in amorphous Fe–Ni–B–Si alloys

The influence of annealing at 520°C on the saturation magnetic field and coercive force of amorphous 2NSR Fe–Ni–B–Si alloys is investigated. As a result of annealing, the saturation magnetic field reaches 1000–1800 Oe. Regions of short-range order (clusters) with a direction in which the atomic pairs are ordered are thought to be formed in the alloys. The formation of the coercive force in amorphous 2NSR alloys is described.

Formation of Magnetic Anisotropy by Lithography.

Artificial interface anisotropy is demonstrated in alternating Co/Pt and Co/Pd stripe patterns, providing a means of forming magnetic anisotropy using lithography. In-plane hysteresis loops measured along two principal directions are explained in depth by two competing shape and interface anisotropies, thus confirming the formation of interface anisotropy at the Co/Pt and Co/Pd interfaces of the stripe patterns. The measured interface anisotropy energies, which are in the range of 0.2–0.3 erg/cm2 for both stripes, are smaller than those observed in conventional multilayers, indicating a decrease in smoothness of the interfaces when formed by lithography. The demonstration of interface anisotropy in the Co/Pt and Co/Pd stripe patterns is of significant practical importance, because this setup makes it possible to form anisotropy using lithography and to modulate its strength by controlling the pattern width. Furthermore, this makes it possible to form more complex interface anisotropy by fabricating two-dimensional patterns. These artificial anisotropies are expected to open up new device applications such as multilevel bits using in-plane magnetoresistive thin-film structures.

Diffusion and induced magnetic anisotropy in nanocrystalline Fe73.5Si13.5B9Nb3Cu1

71Ge tracer diffusion was studied to gain insight into the atomistic transport processes underlying the formation of magnetic anisotropy in nanocrystalline soft-magnetic Fe73.5Si13.5B9Nb3Cu1. The interfacial diffusion characteristic was determined by the residual intergranular amorphous phase, which gives rise to a strongly reduced interface diffusivity compared with grain boundaries in metals. Ge diffusion in the nanocrystallites, which is considered to characterize Si self-diffusion, is much slower than Fe diffusion owing to the D03 order of the Fe3Si nanocrystallites. Slow Si diffusion in the nanocrystallites is identified as the rate-controlling process for the generation of the field-induced magnetic anisotropy.

The anion and cation effects in the magnetic anisotropy of rare-earth compounds: Charge screening by conduction electrons

The formation of magnetic anisotropy (MA) in rare-earth compounds with transition metals has been analyzed. The screening of the charges creating the crystal field by conduction electrons has been shown to play an important role. The calculations took into account the Friedel charge-density oscillations. The model used for RCo5 is the point-charge crystal field including nonuniform screening by conduction electrons with an anisotropic Fermi surface. The mechanisms of strong MA due to light-element impurities (hydrogen and nitrogen) are considered. The effective charge of an impurity can heavily depend on its ionic radius and the characteristics of the Fermi surface (in particular, on the Fermi momentum kF) of the screening electrons. The screening of the cation and anion charge in hydrides and nitrides based on the R2Fe17 and RFe11Ti intermetallic compounds is discussed.

Parallel magnetic fabrics in metamorphic, granitoid and sedimentary rocks of the Branisko and Čierna hora Mountains (E Slovakia) and their tectonometamorphic control

The magnetic anisotropy of rocks from the Branisko and Čierna hora Mountains (West Carpathians) was investigated, and the ferromagnetic and paramagnetic components were separated and found to be roughly coaxial. The magnetic fabrics in metamorphic, granitoid, and sedimentary rocks display very similar patterns of principal susceptibilities. Metamorphites underwent a polyphase prograde and retrograde metamorphis, granitoids were metamorphosed retrogressively, and sedimentary rocks suffered a very weak prograde metamorphism. Retrogressive and progressive Alpine metamorphism and the formation of magnetic anisotropy took place simultaneously, before, during. and after the emplacement of the Central West Carpathian nappes.