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The effect of the stray field of Fe/Fe3O4 nanoparticles on the angular dependence of the microwave absorption derivative in CoFeB/Ta/CoFeB synthetic ferrimagnetic structures and CoFeB films with perpendicular anisotropy is analyzed, and its application for sensor technology is proposed. The effective field of the "platform-particles" system controlled by the magnetic dipole interaction of the CoFeB-Fe/Fe3O4 system decreased to zero in areas where the platform was magnetostatically coupled with nanoparticles. Micromagnetic modeling demonstrated the distribution of magnetization and resistance in local areas of CoFeB/Ta/CoFeB structures under the nanoparticles. The microwave absorption derivative can be used as an indicator of local magnetization switching of the giant magnetoresistance (GMR) structure under scattering fields of NPs or magnetically labeled cells. The limiting sensitivity of the detection method was 2.4 × 107 nanoparticles, which covered the spin-valve surface. We have proposed to combine the advantages of a GMR sensor with wireless technology of microwave reading of magnetoresistance for the detection of magnetically labeled cells.

This paper is about a comparative analysis of the requirements of the Russian standard, the standard of the European Union and the PRC for overhead contact wires for electrified high-speed railways. New generation contact wires must have a high level of mechanical, electrical and operational properties. The Russian standard does not regulate the chemical composition of alloys used for the contact wires manufacture. Unlike the standards of the European Union and China, the Russian standard regulates the maximum value of the relative creep. Compositions, mechanical properties, electrical resistivity and recrystallization temperature for the contact wires with a cross section of 120 mm2 are given. The requirements for the material for the contact wire are presented. The need to use more durable conductive materials instead of copper is noted since mechanical loads and operating temperatures are constantly increasing. The values of mechanical properties, recrystallization temperature and creep of contact wires made of copper alloys are given. Based on the analysis results of the literature data and the experiments, alloys of the Cu-Mg system are recommended as a material for the contact wire manufacture for an overhead network system for high-speed railways.

This paper considers some theoretical provisions on the impact ultrasonic mechanical vibrations have on the throughput of an electroerosive piercing of small-diameter holes. The approximate estimates confirm the hypothesis that the cumulative jets mechanism makes the greatest contribution to the intensification of a multiphase medium flow in the interelectrode gap. A model is proposed for a periodic localization of the cavitation region in the bottom part of the annular side gap. It allows explaining the occurrence of a multiphase medium flow during hole processing.

The article presents an overview of possible technological schemes to produce an overhead contact wire for railways. Pilot experiments were carried out on the manufacture of a contact wire made of CuMg0.3, CuMg0.4 and CuMg0.5 alloys and having a nominal cross section of 100 mm2. The contact wire was obtained from a continuously cast rod with small section, which was subjected to plastic deformation using the Conform technology and cold drawing of the extruded rod. In the casting process, we encountered the formation of cracks on the cast rod surface and the rods breakage. The inner surface of the graphite bushings of the mold after casting the rod was studied and a thin gray layer was found on the inner surface of the graphite bushings. Areas of the graphite bushing with gray layer were studied by scanning electron microscopy and element-by-element mapping was performed with the selection of a spectrum in the sediment layer area. In order to determine the phase composition of the sediment layer it was analyzed by the method of full-profile analysis of the X-ray diffraction pattern according to Rietveld. X-ray phase analysis showed the CuMg2 and Cu2Mg phases presence. This allowed us to assume a possible mechanism for the formation of the sediment layer. Ultimate tensile strength, elongation and electrical resistivity was determined. Analysis showed that the overhead wires made of CuMg0.3, CuMg0.4, CuMg0.5 alloys meets the requirements of GOST R 55647-2018 for wires made of the second conditional group bronze.

The quantum tunneling of magnetization accelerates magnetic relaxation in transition and rare-earth ion complexes and often leads to the degradation of the characteristics of single-molecule or single-ion magnets. On the other hand, the applied dc magnetic field slows down the quantum tunneling of magnetization and favors other channels of spin relaxation. In this work, the stray magnetic field related to ferromagnetic microparticles occurring in the SIM composite with PrDyFeCoB microparticles is proposed instead of the applied field. The adjustable remanent magnetization of microparticles makes it possible to control the required stray field, which can be used to tune the spin relaxation rate in the complexes surrounding the microparticles. In this case, a slow spin relaxation is observed at zero applied field.

The NiFe/Cu/IrMn heterostructures with a variable number of interlayer Cu atoms exhibit a sharp change in the exchange-bias field, the coercive force, and the unidirectional anisotropy field at an effective copper layer thickness tCu ≈ 0.5 nm, which corresponds to incomplete coverage of the interface, i.e., to an island deposited structure. The symmetry of the angular dependence of the ferromagnetic resonance changes sharply at an incompletely coated interface (tCu = 0.5 nm), which corresponds to a transition from isolated islands to a magnetic fractal structure. This phenomenon, which can be called a “magnetic” percolation threshold is not related to the electrical resistance of the heterostructure, which decreases sharply at a significantly larger effective threshold copper layer thickness (tCu = 1.3 nm) when the interface is completely covered.

The article presents the results of pilot-industrial experiments in the field of manufacturing technology of contact wire made of Cu-Sn alloys. Cast rods with a diameter of 20 mm, made of CuSn0.04, CuSn0.1, CuSn0.2, CuSn0.3, CuSn0.4 alloys, were obtained in a continuous casting plant on an Upcast system. Cast rods were deformed using a Conform technology, and extruded billets with a diameter of 18 and 20 mm were produced, which were subsequently drawn on a shaped contact wire with a cross section of 100 mm2. Cast rods macrostructure and microstructure were studied. The macrostructure quantitative assessment of samples was studied in a cross and longitudinal section. A plot of the effect of the tin content in the alloy on the average grain area in cross section is obtained. An increase in the tin content in the alloy leads to a decrease in the average grain area. An analysis of the rod microstructure in a cross section showed that the structure is a grain of an α-solid solution of tin in copper, and the grain boundaries are thin and clean. After deformation by Conform technology a uniform fine-grained structure is ensured. The effect of the tin content in the alloy on the Brinell hardness of cast billets, made by Conform technology, is determined. An increase in the tin content in the alloy leads to an increase in the hardness of both cast and deformed billets. The microstructure analysis of the contact wire in the cross section is carried out. The mechanical and electrical properties of the contact wire with a cross section of 100 mm2 are determined. An analysis of the results showed when the tin content in the alloy is up to 0.4 wt. %, the required level of mechanical and electrical properties of the contact wire is not provided. It may be necessary to change the size of the initial billet before drawing or to increase the tin content in the alloy more than 0.4 wt. %.

This paper demonstrates that 18 μm deep surface understating with a tolerance of 4.5 μm and a roughness Ra=0.4 μm can be produced to the required accuracy by electrochemical die-sinking if configured appropriately.Theoretical analysis shows that the bottom profile error can be presented as a superposition of the errors of surface alignment (non-parallel bottom) and shape (non-flat bottom). In this case, the alignment error accounts for a greater part of the size tolerance (3 μm out of 4.5 μm). This is why the attainment of desired accuracy revolves around the development, analysis, and assessment of ways to reduce this error.

Using selective dissolution, we create α-Fe/DyPrFeCoB microwires with a parabolic tip for focusing the magnetic flux and enhancing the magnetic attraction of particles. The conditions for sharpening the end of the microwire by etching with HNO3 and with mixtures of HNO3 + HCl and H2SO4 + HNO3 are also optimized. The magnetic force of a single microwire with a pointed end (up to 880 pN) makes it possible to capture and hold a DyPrFeCoB microparticle with a size of 1 µm in the region of ~5 µm. A significant magnetic-field gradient (up to ~3.5 × 105 T/m), created at the tip of the microwire, is sufficient to affect biological processes inside cells even without magnetic markers. The conditions for the attachment/detachment of a magnetic microparticle are controlled by the exchange bias arising at the interface between the α-Fe ferromagnetic core and the PrDyFeCoB ferrimagnetic shell and by four magnetic states of the microwire, which are switched by a weak external uniform magnetic field of ~0.1–2 kA/m.

In DyPr–FeCo–B microwires with easy magnetization axis directed along the microwire axis, domains with radial magnetization are detected using magneto-optical indicator films. The width of radial domains decreases as the field increases to 30 mT and increases with the microwire diameter in the range of 60–105 μm. In wires of smaller diameter, the critical field of radial domain formation is lower. The effect of the periodic relief produced by scribing on the magnetization distribution perpendicular to the microwire is detected.

Provides an overview of the magnetism features of amorphous magnets of the RE–TM and RE–TM–B alloys (RE – rare earth metal, TM – transition metal, B – boron). Magnetic states in amorphous alloys, the effect of the single-ionic anisotropy of heavy rare-earth metals on local disorder and spin frustrations in an amorphous body, and some spin-reorientation transitions observed in such compounds are presented. It is shown that the identification of the spin-glass state can be achieved by detecting specific features on the field and temperature dependences of the magnetic moment and magnetic susceptibility of the sample.

In this paper, we present the study of domain structure accompanying interstate transitions in Pt/Co/Ir/Co/Pr synthetic ferrimagnet (SF) of 1.1 nm thick and 0.6 – 1.0 nm thin ferromagnetic Co layers. Variation in the thickness of the thin layer causes noticeable changes in the domain structure and mechanism of magnetization reversal revealed by MOKE (Magneto-Optical Kerr Effect) technique. Magnetization reversal includes coherent rotation of magnetization of the ferromagnetic layers, generation of magnetic nuclei, spreading of domain walls (DW), and development of areas similar with strip domains, dependently on thickness of the thin layer. Inequivalence of the direct and backward transitions between magnetic states of SF with parallel and antiparallel magnetizations was observed in sample with thin layer thicknesses 0.8 nm and 1.0 nm. Asymmetry of the transition between these states is expressed in difference fluctuation fields and shapes of reversal magnetization nucleus contributing to the correspondent forward and backward transitions. We proposed simple model based on asymmetry of Dzyaloshinskii–Moriya interaction. This model explains competition between nucleation and domain wall propagation due to increase/decrease of the DW energy dependently on direction of the spin rotation into the DW in respect to external field.

The article provides the analysis of PrDyFeCoB magnetic microstripes prepared by extracting material from a melt on a rotating cooling disk. The phases 2-14-1, 1-4-1 and 1-2, α-FeСо were verified in the samples. The division of a hysteresis loop into two strands shows that the coercive field of the α-FeСо phase (500–700 Oe) determines the width of the hysteresis loop near the zero field, while the coercive field of the 2-14-1 phase (10 kOe) corresponds to lateral hysteresis loops. The saturation magnetization increases by 25% with an increase in the disk rotation speed by 3 times together with correspondent acceleration of the cooling rate. This is due to the increase in the proportion of the soft magnetic phase α-FeCo and the increase in the proportion of the amorphous phase with a decrease in the proportion of the main magnetic phase 2-14-1. Strip domains and their dynamics during magnetization were detected using Kerr magneto-optical microscopy.

The PrDyFeCoB microwires, whose diameter and cylindricity are controlled via rotation speed of a cooling cylinder and depend on time of droplet solidification on it, are obtained via extraction of a hanging melt droplet. The variations in cooling mode of a melt droplet lead to a change in cross-sectional shape from completely cylindrical to semicircle, crescent, and almost flat plate one. We found that the cooling mode affects not only the morphology, but also the mechanical properties, which are different for microwires of d-ifferent shapes, and changes the microhardness and Young’s modulus of different surfaces of the same microwire.

In a Pt/Co/Ir/Co/Pt synthetic ferrimagnet with perpendicular magnetic anisotropy, a stochastically appearing magnetization peak was found in the field dependence of the magnetic moment at a high sweep rate of the magnetic field of 16 kOe/s and T = 300 K. The peak appears near coinciding switching fields between three equilibrium states of magnetization. The peak is caused by the nucleation of nonequilibrium magnetic domains near structural defects of the cobalt film, where the activation energy of magnetic nucleation decreases.

In a series of NiFe/Cu/IrMn structures with a variable effective thickness of the nonmagnetic copper interlayer (up to its absence in the NiFe/IrMn sample), we observed a decrease in the exchange bias and coercive force with an increase in the effective thickness of the copper layer. The coalescence of copper islands when the effective thickness of the copper layer reaches 1 nm changes the contact exchange interaction between the ferromagnet and antiferromagnet in NiFe–IrMn to indirect exchange interaction through the conduction electrons of the copper layer in NiFe–Cu–IrMn. The structural quality of single-crystal ferromagnetic and antiferromagnetic layers does not change, and the magnetization reversal occurs without the participation of domains in the temperature range of 2–300 K. Simulation of the deposition dynamics demonstrates the island structure of the film at the initial stages up to an effective thickness of 1 nm.

The magnetization reversal of the MgO/CoFeB/Ta/CoFeB/MgO/Ta/GaAs heterostructures and the ultrathin MgO/CoFeB/MgO/Ta/GaAs films with a perpendicular anisotropy in the magnetic field of clusters of Fe/Fe3O4 nanoparticles is experimentally observed. The stray magnetic field of Fe/Fe3O4 nanoparticles increases the field of switching the magnetization of spin valves and monolayer platforms. The size of the magnetization reversal region of the ferromagnetic platform under Fe/Fe3O4 nanoparticles as a function of the cluster size was determined by atomic force and magnetic force microscopy. The size of the magnetization reversal region is found to be larger than the particle cluster size, which is caused by the stray field of a cluster of Fe/Fe3O4 nanoparticles. The local magnetization orientations in the CoFeB layers under clusters of nanoparticles and the magnetization reversal region diameter are determined as functions of the magnetic moment and the size of the cluster using micromagnetic simulation.

The presence of a spin reorientation transition accompanied by a multiple decrease in the longitudinal magnetization of α-Fe/PrDyCoFeB microwires at 245 K in zero magnetic field is revealed. Increasing the applied magnetic field, while the microwire is heated starting from 2 K, leads to a considerable shift in the transition temperature from 245 K at 0 T to 70 K at 1 T. For perpendicular orientation, variation in magnetization at the critical temperature of transition is nearly absent. In weak fields, the microwire’s magnetic anisotropy and magnetic susceptibility exhibit an abrupt change at the critical temperature. The magnetic phase transition is due to a transition between the ferromagnetic state of PrDyCoFeB shell at high temperatures to the state of Ising spin glass at low temperatures.

In the NiFe/Ta/IrMn structures, the contributions of two types of exchange interactions at the NiFe/IrMn interface, partially separated by sections of the nonmagnetic tantalum interlayer, are distinguished. One type of exchange is “contact”—it occurs directly at the NiFe/IrMn interface. Another type is “interlayer,” which takes place through the conduction electrons of the tantalum interlayer. A comparison of the temperature dependences of the exchange bias of the hysteresis loops at fixed parameters of the ferromagnetic layers and various effective thicknesses of the nonmagnetic interlayer made it possible to separate the contributions of the above types of exchange interactions and determine their temperature dependences individually. The exchange interaction energies at the NiFe/IrMn and NiFe/Ta/IrMn interfaces were determined.

The anisotropy of magnetization of microwires consisting of an α-Fe core and a (PrDy)(FeCo)B shell is studied at 300 K. The components of α-Fe core magnetization directed along the microwire axis and the noncollinear component of the microwire shell with different magnetization saturation fields of ~100 Ое and >10 kOe, respectively, are separated. The difference between the directions of magnetization of the shell and the core is 170°.

It has been established that nonmonotonic magnetization relaxation in Pt/Co/Ir/Co/Pt synthetic ferrimagnets (SF) with perpendicular magnetic anisotropy is caused by the coincidence of two or three switching fields between stable states of the SF magnetization (double or triple point). The fields of switching between the stable states of SFs are determined by the ratio of the Zeeman energy, interlayer exchange energy, and the energies of magnetization reversal barriers of each layer, depending on the thickness of the layers and temperature. It has been shown that the selection of thickness and/or temperature enables reaching double and triple points at which the transition fields between the states coincide, which causes a nonmonotonic magnetic relaxation of SFs.

Comparison of spontaneous magnetization losses in (Pr0.51Dy0.49)13(Fe0.64Co0.36)80B7 and (Pr0.51Dy0.49)13(Fe0.64Co0.36)79Cu1B at % sintered magnets shows that copper doping reduces these losses. This is associated with phase homogenization reducing the scattering fields at phase boundaries as well as with an increase in the mean anisotropy field and the coercive force that stabilizes time characteristics of a magnet. It is found that the demagnetization dynamics at room temperature is described by an exponential function.

During the bending operation of the thin sheet materials by the punch with the near-to-zero radius the special technological operation should be carried out. It means that the metal sheet obtained a certain thinning value, which is usually done in the form of the channel-concentrator or groove by pre-drawing operation in a cold state. It follows to the pre-straining and strengthening of the material. The authors investigated the strain hardened sheet's area after roll forming process theoretically, and obtained the strain-stress distribution inside the sheet during the bending operation. It was found out that the increase of the prior deformation during pre-straining in the bend layer follows to the increase of the radial and tangential stresses and displacement of the neutral axis inside the blank during bending operation. As a result, the bending moment changes its values depends on the punch radius and strain hardening.

Here, we study the effect of the Dzyaloshinskii-Moriya interaction (DMI) on magnetic nuclei expansion in Pt/Co/Ir/Co/Pt perpendicular synthetic ferrimagnets. Magnetization reversal is explored as a response to the DMI, affecting the expansion of the magnetic nuclei. We report a nontrivial inverted dependence of the velocity of the double domain wall on the in-plane (IP) magnetic field. This effect is due to competition of the DMI contributions, resulting in effective fields of different signs in the two Co layers. We report a macroscopic manifestation of the DMI as magnetization reversal accelerated by the applied IP magnetic field. Accelerated magnetic relaxation is provided by the DMI-induced ellipticity of the magnetic nuclei, the spreading of which is accompanied by an enhanced number of nuclei contacts in comparison with round nuclei in the absence of an IP field. The obtained results clarify how the DMI contributes to macroscopic magnetic relaxation in the presence of the interlayer Heisenberg exchange interaction in synthetic ferrimagnets with perpendicular anisotropy.

A nanonet consisting of ultrathin Ni nanowires (diameter

We present analysis of the effect of Dzyaloshinskii–Moriya interaction (DMI) on spin wave nonreciprocity and bubble expansion asymmetry in Pt/Co/Ir/Co/Pt synthetic ferrimagnets with perpendicular magnetic anisotropy. We propose analysis of the DMI by Brillouin light scattering technique (BLS) and Kerr microscopy (MOKE) in the presence of interlayer exchange coupling strongly changing spin wave dispersion law and field dependences of domain wall velocity in comparison with those observed earlier in Ir/Co/Pt structures with a single Co layer. We have determined DMI values of each Co layer from unusually inverted dependence of velocity of the domain wall on in-plane magnetic field. Opposite signs of effective fields and DMI fields in the two Co layers invert field dependence of the domain wall velocity. DMI energy determined from BLS is higher than values, determined by bubble expansion.

The purpose of the work is to find the dependence of growth rate of magnetization centers of various types on their surrounding by other nucleation centers in a synthetic Pt/Co/Ir/Co/Pt ferrimagnet with perpendicular magnetic anisotropy. The following four types of nucleation centers exist in a sample with two ferromagnetic layers of different thicknesses: P+ centers correspond to the regions where the magnetizations of the thick and thin Co layers are directed along an applied field (↑↑); P– centers are the regions where the magnetizations of the layers are opposite to an applied field (↓↓); and AP+ and AP– centers correspond to the regions where the magnetizations of the thick and thin Co layers are opposite to each other and the total magnetic moment is along (↑↓) or opposite to (↓↑) an applied field, respectively. P– nucleation centers are found to be surrounded by AP+ regions in any field and exhibit a monotonic field dependence of their boundary. The field dependence of the growth rate of AP– nucleation centers is nonmonotonic since, as the field increases, they are surrounded by AP+ nucleation centers, AP+ and P– regions, and only P– nucleation centers in strong fields.

This article studies dry hobbing of external cylindrical wheels by worm wheel hobs and reasons why some gear manufactures use hobbing without cutting fluids. Cutting fluids reduce frictional wear, provides temperature cooling of the tool or workpiece and helps flush away the chips from the cutting zone. But uneven cooling and different cutting conditions on the engaging and disengaging sides of a gear mesh provoke intensive wear of the teeth of the worm wheel hob, thus decreasing the life of worm hobs and increasing both the consumption of cutting tools and expenses for them. In this context, it becomes rather difficult to achieve efficiency and stability for the hobbing process. In the recent times, the cost of coolant disposal has been raised; in some cases, it accounts for 15-20% in terms of shop costs. Research was carried out under the following experimental conditions: a hobbing machine equipped with an automation system of high efficiency and with basic units of high static and dynamic stiffness; a high-accuracy worm hob from powdered metal wear-resistant high-speed steel of grade Р6М5К5; a workholding device with an elastic bush, and various cutting modes. Recommendations are given on using the multi-cycle hob-shifting strategy rather than the strategy of single-cycle shifting; and advantages gained by this technique are observed. Best cutting conditions and precision attained by dry gear-hobbing are described.

In conventional machining, the process of shaping of products from such new materials as alloys with special properties, composite materials and ceramic materials is rather challenged because of low ductility, intense hardness, diversity of physical and mechanical properties of definite components, etc.

This study investigates the possibility of electrochemical removal of the defective layer formed on the surface of the product after its electrical discharge machining. A set of experiments was conducted in different electrolytes based on aqueous and aqueous-organic solvents. The experiments were to trace the influence of such settings of electrochemical machining as current density, electrolyte pumping speed, electrolyte temperature, and an electrode gap upon both the dynamics of metal removal and surface quality. Morphology of the obtained surface was examined by an Olympus BX-51Microscope. The dynamics of removing material (stock) from the work piece was inspected. Appropriate adjustments were made to the machining parameters during the machining of 65G steels, and a preferred composition was selected for the working medium. A sufficient design for production tools was proposed. Pitting corrosion was discovered on the surface of the samples in all studied modes of electrolysis. It was observed that switching from aqueous electrolyte to aqueous-organic electrolyte gave lower material removal rate and longer machining time accordingly. At the same time, a reduction in surface roughness was visualized, together with smaller pits and lower density of their distribution. The obtained results may be applied in operation design for electrochemical machining of steels with relatively high carbon contents.

We analyzed magnetic force microscopy images of the surface of samples cut parallel and perpendicular to the texture created by applying a field in the process of pressing a magnet. The distribution of the linear size (width) of the domains correlates with the distribution of the projection area of grains onto the shear plane in sintered (PrDy)(FeCo)B magnets with radial magnetization and in prismatic (NdDy)(FeCo)B magnets. The effects of grain size and direction of the axes of easy magnetization of grains on the width of the domains, as the main factors controlling the domain structure, are discussed.

In this paper, we obtained α-Fe(50 at %)(PrDy)(FeCo)B(48 at %) microwires by extraction of a hanging drop of the (PrDy)(FeCo)B melt in the electron beam. A single microwire with a diameter of 50 μm and a length of 0.8–6 mm and with an amorphous (PrDy)(FeCo)B content of ~48% and a polycrystalline α‑Fe phase of ~52% is shown to have a rectangular narrow magnetic hysteresis loop and, accordingly, a bistable state with a switching field of ~100 Oe. Shortening the wire to ~0.6 mm leads to a sharp deviation from the loop rectangularity and a decrease in the slope of the dependence of magnetization on the field and coercive force to 20 Oe. In the near-surface layers consisting of an amorphous phase (PrDy)(FeCo)B, oriented regions of reverse magnetization are observed. The role of the magnetic dipole interaction in the formation of the magnetic hysteresis loop of chaotic ensembles of microwires with various compositions is discussed.

International audience; Irradiation of the heterostructure glass/Ta/Pt/GdFeCo/IrMn/Pt by 50 fs ultra-short laser pulses causes local thinning of the film down to~12-30 nm depth. These pits are distinguished by Atomic Force Microscopy (AFM), while their stray magnetic fields were detected by Magnetic Force Microscopy (MFM). The crater was formed due to layer-by-layer evaporation of the material. No sign of melting was found in the vicinity of the crater at subthreshold laser fluence below 12-15 mJ/cm 2 , but exceeding of the threshold caused destruction of the layers. Energy-dispersive X-ray spectroscopy (EDX) revealed depletion of Gd, Fe and Co, responsible for magnetic properties of the subthreshold crater. The amplitude of the local MOKE signal decreased down to 1.7 times in the irradiated area, while thinning of the ferromagnetic layer was 1.1 times. No proportional change of magneti-zation was caused by bias effect of IrMn layer. Decreased elastic modulus was found inside the subthreshold crater in the irradiated areas. Laser engineering of the surface of GdFeCo thin films opens the way for local control of energy balance between magnetic anisotropy, exchange coupling and Zeeman energy and creation of separated sectors for capture, storage and analysis of the ferromagnetic nanoparticles.

The magnetization losses of the (Pr0.51Dy0.49)13.6(Fe0.64Co0.36)79.6B6.8 and (Pr0.51Dy0.49)13.4(Fe0.64Co0.36)78.8Cu1.1B6.7 magnets are studied. The alloying of the Pr–Dy–Fe–Co–B materials with copper is shown to cause a decrease in the magnetization losses in time, which is due to an increase in the coercive force.

It is shown that the shape of a sample determines the allowed lower-bound limit of the coercive force of material that can be used for fabrication of magnets with the given shape. Rings with radial magnetization are used as examples to show that such samples can be made of only rare-earth alloys with the coercive force that is sufficiently high to satisfy technical requirements at the maximum allowed working temperature of the magnet.

This article is devoted to the effect of a magnetic field of 0.7 T on the state of an aluminum alloy whose creep increases after exposing to a magnetic field, exhibiting a “magnetic memory.” The alloy contains FeAl microinclusions identified by electron microscopy, magnetometry, and Mossbauer spectroscopy. Possible mechanisms of changing the states of ferromagnetic microinclusions and aluminum matrix around them under a magnetic field are discussed.

Magnetic anisotropy values are obtained for [(Co41Fe39B20)x(SiO2)100 – x/Bi2Te3]47 heterostructures consisting of SiO2 alternating layers, CoFeB nanoparticles distributed in them, and Bi2Te3 layers with ferromagnetic resonance and magnetometry. The heterostructures have anisotropy of ~106 erg/cm3, which orients the magnetic moment in films plane. The films are not solid, but they disintegrate into CoFeB nanoparticles with an average diameter of 5 nm during deposition, which corresponds to the blocking magnetization temperature of ~30 K during their saturation magnetization of MS = 720 emu/cm3. The relationship between anisotropy constant and thickness of the layers of the heterostructures is nonmonotonic due to competition between surface and bulk anisotropies of the ferromagnetic granules, which the films are made of.

Magnetization reversal in NiFe/IrMn exchange-biased thin films was investigated under thermal cycling in an external magnetic field, applied opposite to the direction of the exchange bias field. Thermal hysteresis of magnetization accompanied by changes in magnetization polarity was observed in the applied field close to the exchange bias value. This effect appears when thermally induced variations of the exchange bias exceed the corresponding variations in coercivity. The amplitude of magnetization reversal in NiFe/IrMn structures exceeds ∼100 times the corresponding amplitude in spin-crossover molecular compounds. The observed bistability of the magnetic state, revealed by thermal hysteresis, gradually disappears with an increase in the number of cooling–heating thermal cycles, that indicates an irreversible quenching of the interfacial magnetization configuration. This effect paves the way for the creation of a new class of switching devices with thermally assisted bistability in the ferromagnetic state.

Magnetocaloric effect (MCE) in an antiferromagnetic holmium (Ho) film is studied near the spin reorientation temperatures. A series of magnetization isotherms from 60 to 150 K around the N\'eel temperature, ${T}_{N}\ensuremath{\approx}130\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ were recorded for both in-plane and out-of-plane magnetic field orientations. A change in entropy, $\mathrm{\ensuremath{\Delta}}{S}_{M}$ of $\text{--}5\phantom{\rule{0.28em}{0ex}}\mathrm{J}/\mathrm{kg}\mathrm{K}$ was found near ${T}_{N}$ for an in-plane field orientation. A large change in $\mathrm{\ensuremath{\Delta}}{S}_{M}$ of \ensuremath{-}11.8 J/kg K due to a fan-helix spin transition at $T=90\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ is observed for an in-plane field orientation. Spin transition at both ${T}_{N}$ and at the fan-helix transition exhibit larger MCE in the in-plane field orientations in comparison with the perpendicular orientation. The value of the refrigerant capacity extracted from the temperature dependence of $\mathrm{\ensuremath{\Delta}}{S}_{M}(T)$ is found to be larger for the ``in- plane'' orientation by a factor of two.