The development of magnetic particles for cell separation is a promising and actively developing direction. An important requirement for this method of isolation is the preservation of cell viability for the possibility of further study. The aim of the work was to develop magnetic composites based on iron oxide for single-stage cell separation and to evaluate the possibilities of further study of these cells using molecular and cellular biology methods. The particles were synthesized by the precipitation method; the magnetic cores were embedded in silica using TEOS and APTES reagents. Anti-EpCAM antibodies were immobilized on the surfaces of the obtained composites. T24 cells containing this antigen on the surface of some cells were used as a model suspension. It was shown that incubation of particles with the cells led to a decrease in the proportion of EpCAM-positive cells in the suspension and their binding to the magnetic composites. During the first hour of incubation with the particles, a decrease in the proportion of living cells in the suspension and a change in the mRNA level of the BCL2 gene were noted. However, after 2 h of incubation, cell adaptation and restoration of viability were noted. The separation procedure resulted in a stable decrease in the expression of the BIRC5 gene. The cells that were immobilized were subsequently successfully cultured. Thus, the proposed particles do not have high requirements for synthesis but allow for the isolation of living cells that can be used for further studies.

Results are presented from investigating the ferromagnetic resonance spectra of arrays of Co‒Ni and Co‒Fe‒Ni wires with different composition gradients, deposited into polycarbonate track-etched membranes. The effect interfaces and concentration gradients have on the effective fields of the investigated wires is examined. An anomalous angular dependence of the fields of ferromagnetic resonance is observed for the wire arrays at a pore density of 18

We discussed experimental results concerning the ferromagnetic resonance spectra characteristics of Co-Ni and Co-Fe-Ni wires arrays with different gradients of composition deposited into porous of track etched polycarbonate membranes. The influence of interfacial boundaries and concentration gradients on the effective field of the investigated wires has been studied. An anomalous angular dependence of the FMR resonance fields is observed for wires arrays with a membrane pore density of ~18%.

The study investigates carbon-containing coatings of 3d-metals (Ni, Co, Fe) produced by chemical deposition method using arabinogalactan. The coatings were analyzed using X-ray diffraction, FMR, and M(H) magnetometry. Measurement of M(H) in plane and perpendicular to the plane of the magnetic coatings allowed determining the distribution of demagnetizing factor in the studied coatings. The obtained distributions of the demagnetizing factor were used to analyze the angular dependences of the ferromagnetic resonance field. The values of magnetization and perpendicular anisotropy field were estimated. The paper illustrates the effect of texture on the magnetic parameters.

Multilayered [Cu(3 nm)/FeNi(100 nm)]5/Cu(150 nm)/FeNi(10 nm)/Cu(150 nm)/FeNi(10 nm)/Cu(150 nm)/[Cu(3 nm)/FeNi(100 nm)]5 structures were obtained by using the magnetron sputtering technique in the external in-plane magnetic field. From these, multilayer magnetoimpedance elements were fabricated in the shape of elongated stripes using the lift-off lithographic process. In order to obtain maximum magnetoimpedance (MI) sensitivity with respect to the external magnetic field, the short side of the rectangular element was oriented along the direction of the technological magnetic field applied during the multilayered structure deposition. MI sensitivity was defined as the change of the total impedance or its real part per unit of the magnetic field. The design of the elements (multilayered structure, shape of the element, etc.) contributed to the dynamic and static magnetic properties. The magnetostatic properties of the MI elements, including analysis of the magnetic domain structure, indicated the crucial importance of magnetostatic interactions between FeNi magnetic layers in the analyzed [Cu(3 nm)/FeNi(100 nm)]5 multilayers. In addition, the uniformity of the magnetic parameters was defined by the advanced technique of the local measurements of the ferromagnetic resonance field. Dynamic methods allowed investigation of the elements at different thicknesses by varying the frequency of the electromagnetic excitation. The maximum sensitivity of 40%/Oe with respect to the applied field in the range of the fields of 3 Oe to 5 Oe is promising for different applications.

Study of the mechanisms of the solid-state reactions in Sn/Fe/Cu thin films is interesting both from a fundamental point of view and from a view of the importance of emerging intermetallics in the technology of solder joints and thin-film lithium-ion batteries. By the integrated approach, including both X-ray phase analysis and local elemental analysis of the cross-sections of the films, the phase composition and the mutual arrangement of phases were studied, at various stages of the solid-state reaction occurring at different temperatures. The observed sequence of the appearing phases differs significantly from the expected one if the mass transfer took place by a volume diffusion through the forming layers.

Mn5Ge3 is a ferromagnetic hexagonal crystal promising for spintronics and magnetocalorics. A systematic study and analysis of the magnetic properties of the Mn5Ge3 thin film grown on Si(111) were performed. The magnetic anisotropy of the film is determined by the shape anisotropy and the easy magnetization axis aligned along the c axis of the crystal. The uniaxial anisotropy constant Ku fully corresponds to that for a bulk single crystal, which indicates that c axis coincides with film normal. Mn5Ge3 film demonstrates high saturation magnetization MS = 900 emu/cm3 (900 kA/m) at T = 100 K and magnetocaloric effect ΔS = 3.16 ± 0.22 J kg−1 K−1 at 300 K and B = 1.5 T. ΔS is comparable to that for multicomponent or Gd rare earth films. Furthermore, a different anisotropy of the magnetocaloric effect compared to bulk Mn5Ge3 was found, which may be related to the anisotropy of the film shape and, possibly, to the domain structure. The results obtained are promising for the design and development of magnetocaloric, spintronic, and spin-caloritronic devices on a silicon platform.

The structure and phases formed in Sn/Co thin films are interesting both from the solid-state chemistry point of view and due to applications of such a metallic bilayer. The phases forming in thin films Sn/Co obtained by thermal vacuum evaporation on two different substrates SiO2 and MgO(100) at different annealing temperatures have been studied. Annealing above 110 degrees & Scy; results in intermetallics formation in the films. The hcp-cobalt is grown in the films on SiO2 substrate, and the fcc-Co is observed on MgO(100) substrate. It is found that the stable alpha-Co3Sn2 intermetallic is formed at higher annealing temperature in film on MgO(100) substrate. We show that transformations related to mass transfer in the Sn/Co bilayers were up to 500 degrees & Scy; and were finished upon reaching the thermodynamically equilibrium phase composition at this temperature.

The structure and phases formed in Sn/Co thin films are interesting both from the solid-state chemistry point of view and due to applications of such a metallic bilayer. The phases forming in thin films Sn/Co obtained by thermal vacuum evaporation on two different substrates SiO2 and MgO(100) at different annealing temperatures have been studied. Annealing above 110 °С results in intermetallics formation in the films. The hcp-cobalt is grown in the films on SiO2 substrate, and the fcc-Co is observed on MgO(100) substrate. It is found that the stable α-Co3Sn2 intermetallic is formed at higher annealing temperature in film on MgO(100) substrate. We show that transformations related to mass transfer in the Sn/Co bilayers were up to 500 °С and were finished upon reaching the thermodynamically equilibrium phase composition at this temperature.

Arrays of iron nanowires (NWs) obtained by template-assisted electrodeposition constitute a promising composite material characterized by a combination of high magnetization in the filler and perpendicular magnetic anisotropy. The properties of these composites arise from the interplay between the behavior of individual NWs and their magnetostatic interactions. In this study, we investigated NW arrays with identical wire diameters but varying spatial arrangements. Major hysteresis loops were studied under various field directions relative to the NW axis. Key parameters such as the slope of the magnetization curve, saturation magnetization, and coercive force were quantified. Additionally, FORC (First Order Reversal Curve) measurements were conducted with the field oriented longitudinally with respect to the NW, offering insights into the inhomogeneity of the demagnetizing field influenced by the NW array's configuration. In the sample with the highest NW density, we observed isotropic behavior of the effective demagnetizing field, and we proposed an explanation for this phenomenon using the effective media approach. Micromagnetic simulations revealed that the magnetic behavior of individual NWs with a 100 nm diameter can be described as an interchange between volumes characterized by vortex and uniform magnetization patterns. Calculations of the demagnetizing field using the effective medium model demonstrated excellent agreement with experimental data across arrays featuring different NW densities. Remarkably, the quantitative consistency of coercive field values obtained from micromagnetic simulations and experimental measurements in the range of angles from 0 degrees to 45 degrees for the studied samples underscores the structural homogeneity of the obtained NWs.

The generally accepted model of the magnetic structure of an iron oxide core–shell nanoparticle includes a single-domain magnetically ordered core surrounded by a layer with a frozen spin disorder. Due to the exchange coupling between the shell and core, the spin disorder should lead to nonuniform magnetization in the core. Suppression of this inhomogeneity by an external magnetic field causes the nonlinear behavior of the magnetization as a function of the field in the region of the approach to magnetic saturation. The equation proposed to describe this effect is tested using a micromagnetic simulation. Analysis of the approach to magnetic saturation of iron oxide nanoparticles at different temperatures using this equation can be used to estimate the temperature evolution of the core–shell coupling energy and the size of the uniformly magnetized nanoparticle core and the temperature behavior of this size.

Magnetic nanoparticles of magnetite with a size of ~8 nm synthesized with a different type of coating were studied by ferromagnetic resonance in the temperature range from 7 to 300 K. The features of the experimental temperature dependences of the parameters of the ferromagnetic resonance curve (the magnitude of the resonant field, line width and intensity) and their approximation allowed us to estimate the values of characteristic temperatures. Firstly, the value of the Vervey temperature and the dependence of its value on the type of coating were determined. Secondly, the temperature of transition of nanoparticles to the superparamagnetic state (blocking temperature) and the temperature range within which the magnetic structure of the outer shell of the magnetic nanoparticle is in the spin glass state are established Keywords: iron oxide nanoparticles, ferromagnetic resonance, superparamagnetism, blocking temperature.

Magnetic nanoparticles of magnetite with a size of ~8 nm synthesized with a different type of coating were studied by ferromagnetic resonance in the temperature range from 7 to 300 K. The features of the experimental temperature dependences of the parameters of the ferromagnetic resonance curve (the magnitude of the resonant field, line width and intensity) and their approximation allowed us to estimate the values of characteristic temperatures. Firstly, the value of the Vervey temperature and the dependence of its value on the type of coating were determined. Secondly, the temperature of transition of nanoparticles to the superparamagnetic state (blocking temperature) and the temperature range within which the magnetic structure of the outer shell of the magnetic nanoparticle is in the spin glass state are established

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.

The paper discusses schemes for implementing magneto-mechanical anticancer therapy and the most probable scenarios of damaging mechanical effects on the membranes of malignant cells by targeted magnetic nanoparticles (MNPs) selectively bound to membrane mechanoreceptors employing aptamers. The conditions for the selective triggering of the malignant cell apoptosis in a low-frequency non-heating alternating magnetic field, corresponding to the exceeding threshold value of the force acting on the membrane and its mechanoreceptors, are established using a nanoparticle dynamic simulation. The requirements for the functionality of MNPs and their suitability for biomedical applications are analyzed. Attention is paid to the possibility of the formation of magnetite nanoparticle aggregates in an external magnetic field and their localization near tumor cell membranes. It is shown that the scenario involving the process of aggregation of magnetite nanoparticles provides a sufficient magneto-mechanical impact to achieve a therapeutic effect. A possible explanation for the experimentally established fact of successful application of magneto-mechanical therapy using magnetite nanoparticles is presented, in which complete suppression of the Ehrlich carcinoma in an alternating magnetic field as a response to a magneto-mechanical stimulus was demonstrated. This result confirmed the possibility of using the method for high efficiency treatment of malignant neoplasms. The paper provides an extensive review of key publications and the state of the art in this area.

The structural and magnetic properties of nanostructured Fe 100-x Ni x -C (0<x<100) coatings produced by electroless plating with different carbohydrates as reducing agents have been investigated. The phase-structural state of the films was studied by diffraction and electron microscopy. The Ni concentration ranges of FCC and BCC phases existence in electroless deposited films were determined. The surface morphology, saturation magnetization, local magnetic anisotropy field and coercivities of films are dependent on the iron content and type of reducing agent. The correlation between coercivity H c and the anisotropy field of the magnetic stochastic domain which were established by correlation magnetometry suggests that the magnitude of H c is mainly determined by this anisotropy. Keywords: 3d-metal alloys, the approach to saturation magnetization law, coercivity.

Study of the mechanisms of the solid-state reactions in Sn/Fe/Cu thin films is interesting both from a fundamental point of view and from a view of the importance of emerging intermetallics in the technology of solder joints and thin-film lithium-ion batteries. By the integrated approach, including both X-ray phase analysis and local elemental analysis of the cross-sections of the films, the phase composition and the mutual arrangement of phases were studied, at various stages of the solid-state reaction occurring at different temperatures. The observed sequence of the appearing phases differs significantly from the expected one if the mass transfer took place by a volume diffusion through the forming layers.

The phases, microstructure, and magnetic properties in a severely deformed Cr-Ni–Al alloy have been studied. The eutectic microstructure observed in localized regions of the alloy can be interpreted as a result from the super-Arrhenius relaxation of the alloy. According to X-ray diffraction and magnetometry, the nanosized nickel inclusions in the matrix of the chromium-nickel γ-solid solution are formed. It is shown that, after severe (superplastic) deformation, a unidirectional magnetic anisotropy is induced, which may be associated with the antiferromagnetic coupling between the CrNi 2 matrix and the nickel inclusions.

Investigation of the temperature evolution of magnetization curves near magnetic saturation makes it possible to extract new information on the features of the phase composition and structure of hypoeutectoid steel. It is shown that the main contribution to the magnitude and the temperature behavior of the energy density of the local magnetic anisotropy of hypoeutectoid steel is due to the lamellar structure of pearlite. The peculiarity of the temperature behavior of the energy of the magnetic anisotropy, along with the behavior of the paraprocess, indicates the formation of Mn-substituted cementite in the studied steel sample. The observation of the crossover of power-law regularities in the approximation of magnetization to saturation indicates the formation of two-dimensional nano-inhomogeneities of the local axis of easy magnetization in the plates of alpha iron, which are part of the pearlite.

A comparative study of the magnetic properties of arrays of Co–Ni rods with different composition gradients (smooth or step-like) along the rod axes was carried out. Ordered arrays of Co–Ni nanorods with diameters up to 400 nm and 8 µm length were prepared by electroless plating into a porous nuclear-track-etched polycarbonate membrane. The gradient in Co and Ni composition was confirmed by energy-dispersive X-ray analysis. The variation of Co–Ni contents along the long axis of the rods correlates with the gradient of the magnetization within the rod. Magnetization reversal was studied by analyzing the angular dependence of coercivity and using micromagnetic simulations. For both types of gradient rods, reversal occurs by curling. The local magnetic anisotropy field of rods with a step-type gradient is significantly higher than that for rods with a smooth gradient.