Subsystem domination influence on magnetization reversal in designed magnetic patterns in ferrimagnetic Tb/Co multilayers

Recent results showed that the ferrimagnetic compensation point and other characteristic features of Tb/Co ferrimagnetic multilayers can be tailored by He+ ion bombardment. With appropriate choices of the He+ ion dose, we prepared two types of lattices composed of squares with either Tb or Co domination. The magnetization reversal of the first lattice is similar to that seen in ferromagnetic heterostructures consisting of areas with different switching fields. However, in the second lattice, the creation of domains without accompanying domain walls is possible. These domain patterns are particularly stable because they simultaneously lower the demagnetizing energy and the energy associated with the presence of domain walls (exchange and anisotropy). For both lattices, studies of magnetization reversal show that this process takes place by the propagation of the domain walls. If they are not present at the onset, the reversal starts from the nucleation of reversed domains and it is followed by domain wall propagation. The magnetization reversal process does not depend significantly on the relative sign of the effective magnetization in areas separated by domain walls.

Accounting for Magnetic Saturation Effects in Complex Multi-harmonic Model of Induction Machine

Computations of quasi-dynamic electromagnetic field of induction machines using the complex magnetic vector potential require the use of the so-called effective magnetization curves, i.e., such in which the magnetic permeability is proportional to the amplitudes of magnetic flux density B or magnetic field strength H, not their instantaneous values. There are several definitions of that parameter mentioned in the literature provided for the case when B or H are monoharmonic. In this paper, seven different methods of determining the effective magnetization curves are compared in relation to the use of a field-circuit multi-harmonic model of an induction machine. The accuracy of each method was assessed by computing the performance characteristics of a solid-rotor induction machine. One new definition of the effective permeability was also introduced, being a function of multiple variables dependent on amplitudes of all the harmonics considered. The analyses demonstrated that the best practical approach, even for the multi-harmonic case, is to express the effective magnetic permeability as the ratio of the amplitudes of the fundamental harmonics of the magnetic flux density and the magnetic field strength, and assuming the sinusoidal variation of the latter.

FexNi100-x Thin Film Systems with Slight Deviations from Zero Magnetostriction Compositions: Focus on Pressure Sensor Applications

The structure, magnetic properties, ferromagnetic resonance and giant magnetoimpedance effect (GMI) were studied in FexNi100-x thin films and multilayered systems having compositions with small deviation from zero magnetostriction in order to find the best conditions for possible applications in the area of small pressure sensors. A comparative analysis of the effective magnetization and g-factor was carried out for the thin films of FexNi100-x (x = 19.8, 17.5, 15.0, 11.9) alloys. Comparison of the concentration dependences for static 4πMs and dynamic 4πMeff magnetization values allows to select a narrow interval of concentrations around Fe15Ni85 for the development of a microfluidic small pressure sensitive elements based on GMI effect. The maximum value of GMI ratio (ΔZ/Z) ratio shows linear dependence on the iron content in the FexNi100-x alloy for the concentration range under consideration.

Influence of Magnetic Anisotropy on Inverse Spin Hall Voltage

Spin pumping efficiency (SPE) in a ferromagnetic (FM)/Pt system relies on the effective magnetization damping of FM layer and the interface spin mixing conductance. However, there are very few studies on the influence of magnetic anisotropy of FM material on SPE. In this study, the spin pumping induced spin voltage [Formula: see text] in Fe3O4(58.9[Formula: see text]nm)/Pt(5.5[Formula: see text]nm) is investigated in two different orientations of the external magnetic field, one parallel and other perpendicular to the in-plane easy axis of Fe3O4. The value of [Formula: see text] with the magnetic field along the easy axis is 38% higher compared with that along the hard axis. The possible origin of this enhancement is investigated based on the model of ferromagnetic resonance induced spin pumping.

Structure and Magnetic Properties of FeNi/Ti Multilayered Films Grown by Magnetron Sputtering

Structure and magnetic properties of FeNi/Ti multilayers prepared by magnetron sputtering were studied. The dependences of the spontaneous magnetization and hysteresis features of the films on the thickness of the magnetic layers were established. It was shown that these properties were to a large extent determined by interlayer interfaces, in which the effective magnetization decreases. The possible reason for the interface peculiarities was the interlayer mixing. The presence of (FeNi)Ti phase which was formed by the interdiffusion of FeNi and Ti layers was confirmed by X-ray diffraction measurements.