SPIN

FeNi films were prepared by oblique deposition onto glass substrate using magnetron sputtering deposition technique. The deposition was carried out on a rotating or nonrotating substrate with or without a constant magnetic field applied parallel to the substrate plane. The magnetic properties of the samples were measured by a magneto-optical Kerr effect at room temperature. All films had in-plane uniaxial magnetic anisotropy. The presence of in-plane magnetic anisotropy was also confirmed by the features of the domain structure. The main factor determining the orientation of the induced anisotropy axis of films was the magnetic field applied during deposition.

Co-based rapidly quenched amorphous ribbons are soft ferromagnets with well-adjustable functional properties. Their effective magnetic anisotropy and magnetization processes depend on the preparation conditions and geometrical parameters. It was found that giant magnetoimpedance effect (MI) for the FeCoCrSiB ribbons without heat treatments after relaxation annealing and after stress annealing at 350^∘C shows critical dependence on the value of the demagnetizing factor. The range of FeCoCrSiB ribbons lengths with a significant change in properties is considered in a comparative analysis of the experimental results and model calculations. Quantitative analysis of the contribution of the demagnetizing fields and surface magnetic charges are discussed as the main mechanism for reducing the GMI properties of amorphous ribbons. These data are important for the development of the ribbon-based devices for practical applications of microelectronics.

Basically, this study was carried out in the context of the development of ferrogel-based biocompatible soft tissue implants, in particular, for the needs of regenerative medicine and replacement therapy. The magneto-deformation effect (MDE) of ferrogels (FGs) and the possibility of its visualization with the use of medical ultrasound were in the focus of this work. The aim of this investigation was addressed to search a possible relationship between the extent of MDE and the intensity of the reflected echo signal at the gel/water interface and in the gel interior. Cylindrical FGs $\sim 12$mm in diameter and $\sim 7$mm in height based on polyacrylamide (PAAm) with interpenetrating physical network of natural polysaccharide (Guar) filled with 200–300nm Fe₃O₄ magnetic microparticles (MPs) with weight fraction of 12% or 23% were investigated. MDE was studied using an ultrasonic medical device Sonoline Adara (Siemens, Germany), and estimated by the relative compression of FGs after application the constant gradient magnetic field (MF) up to 500 Oe by an electromagnet. Viscoelastic and acoustic properties of FGs in the absence of the application of an MF were determined as well. It was found that an increase of the weight fraction of MPs in FGs resulted in the significant increase of the ferrogel’s density, the elastic storage modulus, the loss modulus, the acoustic impedance, the reflection coefficient and some decrease of the ultrasonic velocity in FGs. At a given MPs concentration, the MDE in FGs was increased according to a quadratic law with the gradual increase of MF strength. The growth of MDE in FGs accompanies by an increase in the intensity of the reflected echo signal both from the gel/water interface and from the interior of the FGs. The obtained results are discussed from the viewpoint of the effects of MPs on the interaction of an ultrasonic wave with the structure of FGs in the course of MF application.

This study deals with a phenomenon of magnetic domain transition of adjacent narrow thin film strips with inclined uniaxial magnetic anisotropy. Our previous research shows that individual element with 70° inclined easy magnetization axis has a typical characteristic of the domain transition, and the transition can be controlled by the normal magnetic field. We also applied this phenomenon and controlling method to the two-dimensional configuration of line arrangement adjacent to many-body elements, in which mutual magnetic interaction exists. The result shows that the hidden inclined Landau–Lifshitz domain appears by applying a distributed normal field the same as an individual single element. This paper reports a comprehensive magnetic property, such as magnetic domains, magnetic hysteresis-loop (MH-loop), and high-frequency permeability of the adjacent many-body elements, in some fabrication conditions surrounding the exact condition where the hidden inclined Landau–Lifshitz domain appears. The result shows an estimation of a switched device of high-frequency permeability caused by the switched magnetic domain using the hidden domain and the control of distributed normal field. This phenomenon would be expected to apply functional devices, such as a switched inductor or a switched electromagnetic shielding, or a magnetic sensor.

The results of investigation of the distribution of electrical and magnetic properties over the cross-section are presented for Cu${}_{98}$Be₂/Fe${}_{20}$Co₆Ni${}_{74}$ composite wire of the “highly conductive core-magnetically soft coating” type, obtained by electrolytic deposition of the FeCoNi layer. Studies performed by the magneto-impedance tomography (MIT) made it possible to determine the specific electrical conductivity of the materials of the core and coating. It was established that the electrodeposited coating had a magnetic structure that was inhomogeneous over the thickness.

Using Monte Carlo simulation and mean field approximation, we studied the magnetic properties of spin-3/2 chain with hexagonal spin-1/2 shell and negative core-shell exchange coupling. The obtained results show that the spins 3/2 in the core have an important influence on the magnetic behavior of the system such as the appearance of compensation temperatures as well as first- and second-order phase transitions. Moreover, we investigated the effects of exchange interactions and anisotropy on the phase diagrams of the system.

We present results of magneto-optical investigations of (CoFeZr)${}_x$(Al₂O${}_3{)}_{100-x}$ film nanocomposites in transverse Kerr effect (TKE) geometry in the spectral range 0.5–4.0eV and magnetic field up to 3.0kOe. Nanocomposites were deposited onto a glass-ceramic substrate by ion-beam sputtering. The TKE response at room temperature strongly depends on the wavelength of light, applied magnetic field H and the volume metallic fraction. From the analysis of the field dependences of TKE at different wavelengths, it follows that in the as-deposited samples, the interaction between nanoparticles at $x<30$at.% is small and the nanocomposite is an ensemble of superparamagnetic particles; as x increases to 32at.%, a superspinglass-type state arises, then, in the vicinity of 34at.%, along with individual superparamagnetic particles, superferromagnetic regions appear. Long-range ferromagnetic order arises at concentrations x less than the percolation threshold for conductivity $x_{\mathrm{\text{per}}}=42.6$at.%. In the presence of two different magnetic states in the samples, TKE is not proportional to the magnetization. Both the field dependences at near-infrared region and the spectral dependences of TKE change significantly after annealing of the samples, while the changes in the field dependences of the magnetization are almost imperceptibly.

The D0${}_{22}$–Mn₃Ga ferrimagnet promises potential applications in spintronics due to its low magnetization, strong perpendicular magnetic anisotropy and high Curie temperature. In the form of thin and thick films, these properties are preserved. Here, we report on the structural and magnetic characterization of epitaxial D0${}_{22}$–Mn${}_{2.6}$Ga ultrathin films with thicknesses of 2nm, 5nm and 8nm grown on Cr buffer layers by magnetron sputtering. We found that the films are perfect single crystals with flat surfaces and Curie temperatures higher than 300K. The 2nm-thick ultrathin film has higher magnetization than that of the thicker films, likely due to uncompensated ferrimagnetic planes, along the c-axis, linked to the surface roughness at the atomic scale. These properties highly suit the requirements for the elaboration of spintronic devices such as magnetic tunnel junctions.

The influence of iron non-stoichiometry variation on structural, magnetic and dielectric properties in Cobalt ferrite is reported. Cobalt ferrite with compositional formula CoFe${}_{2\pm x}$O₄ ($x=0$, $\pm 0.02$) was prepared through sol-gel synthesis route and sintered at 900^oC/2h. X-ray diffraction confirms the phase evolution of ferrite with additional impurities belonging to $\alpha$-Fe₂O₃ phase and this additional phase disappears for iron deficient sample. The (311) peak shifts towards lower angle for the excess iron sample, whereas it shifts towards higher angle for iron deficient one, confirming the variation in the iron non-stoichiometry. Raman data substantiate the presence of vibrational bands assigned to metal ions in the cobalt ferrites. Change in the peak intensities and peak angle in Raman spectra clearly suggests the movement of cations among octahedral and tetrahedral sites leading to dilution of magnetic character of the samples. Saturation magnetization drastically drops by $\sim 20$% for iron rich and deficient samples but an improvement in coercivity for the iron deficient cobalt ferrite clearly hints the role of anisotropy. A change in dielectric constant value further alludes to the change of iron ions in different valency states.

By the use of Monte Carlo simulation, we have investigated the phase diagrams and magnetic properties of a ferrimagnetic Ising multilayer system with mixed spins (1, $1∕2$). The ground-state phase diagrams are first constructed for $T=0K$. To examine the influences of certain physical parameters of the system, namely the exchange interactions, the number of layers and the crystal field, we have studied the thermal behavior of the system magnetizations and the corresponding phase diagrams. The results obtained in this work show the existence of second- and first-order phase transitions and compensation temperatures. Moreover, we have investigated the hysteresis behavior, where the multi-loop phenomena are observed.

This paper presents the results of investigating the impact of temperature on the magnetic properties of Co/Gd/Co and Co/Cu/Co thin-film three-layer systems obtained via ion-plasma magnetron sputtering. The following features of the studied samples were found. In particular, when the temperature changes from 100 to 300K, the coercive force of studied systems decreases. The magnetic moment of Co/Cu/Co sample does not dependent on temperature. Strong influence of temperature on the magnetic properties of the studied samples is observed. In particular, a compensation point was found at temperature $T=150$K for a Co/Gd/Co sample with thickness of gadolinium of 9.0nm.

Ni nanoparticles layer of nominal thickness in the range of 5–40nm were deposited on polyvinyl alcohol (PVA) film by using the ion beam sputtering (IBS) technique. PVA films were made on a quartz substrate by the solution casting technique. Grazing incidence X-ray diffraction (GIXRD) results reveal Ni is present in a metallic form in the FCC phase. AFM shows that roughness increases with increase in thickness of Ni layer and corresponding MFM images of magnetic domains were recorded. Soft X-ray absorption spectroscopy (SXAS) studies on the PVA/Ni nanocomposites films were recorded using synchrotron radiation. This study is used to study the electronic structure of the as-prepared nanocomposite films and reveals that Ni nanoparticles are present in their metallic form. Magnetic properties were measured using the magneto-optical Kerr effect (MOKE) magnetometer and the films were found to be magnetically soft with higher value of coercivity at lower thickness of Ni nanoparticles layer. The results of magnetic studies are discussed in light of the microstructure and morphological features of PVA/Ni nanocomposite films. The PVA/Ni nanocomposites showed interesting anisotropic magnetic behavior; thus the investigative results may be useful for the development of futuristic flexible functional magnetic material system.