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Ferromagnetic microparticles significantly affect spin relaxation in the Er3+ single-ion magnet sandwiched in a composite material. The balance of thermal spin noise corresponding to Orbach, Raman, quantum tunneling, and direct relaxation channels is shifted in Er3+ complexes under the influence of surrounding ferromagnetic matrix. There are two competing sources of the electron spin noise controlled by ferromagnetic media. First, internal residual magnetic field delays spin relaxation in the Er3+ complexes due to the Zeeman interaction of the Er3+ spin even in the absence of external magnetic field. Second, chemical bonding between the Er 4d shell and the O 1s shell accelerates magnetic relaxation in the Er3+ ions on the surface of microparticles. Significance of these results is that composite media can be sliced into small elements with a variable frequency of spin noise depending on individual magnetization programmed within each element.

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.

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.

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.

Stable crystalline complexes of Co(II) acetylacetonate [Co(II)(acac)2], trifluoacetylacetonate [Co(II)(tfac)2] and hexafluoroacetylacetonate [Co(II)(hfac)2] with triphenodioxazines (TPDOs) were synthesized and their structures studied using X-ray crystallography. In the crystal, complexes [Co(II)(tfac)2]TPDO and [Co(II)(hfac)2]TPDO form infinite ⋯N⋯Co⋯N⋯ chains featuring 1D coordination polymeric structures, whereas in the [Co(II)(acac)2]TPDO complex, the Co(acac)2 units fill only half of the possible crystallographic positions. The electron accepting trifluoro substituents in the diketonate moieties significantly enhance the thermal stability of the complexes with TPDO. Of all the complexes, only [Co(II)(hfac)2]TPDO does not dissociate into the components in solution. In all studied complexes, the Co(II) atom is in a high-spin state and has distorted octahedral surroundings. Distortion of the octahedral polyhedrons appears as axial stretching of the octahedrons along the Co–N bonds; it is due to the specific features of the crystalline structure of the metal polymeric chain in the compounds.

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.

A new copper(II) complex (I) was obtained by the reaction of a sterically crowded 2,4-di-(tert-butyl)-9-chloro-benzo[5,6][1,4]oxazine[2,3-b]phenoxazine bridging ligand with Cu(II) hexafluoroacetylacetonate. Compound I is a quasi-one-dimensional complex in which the Cu(hfac)2 moieties are co-crystallized with the triphenodioxazine molecules through only weak Cu⋯N short intermolecular interactions (the Cu⋯N distances are 2.732 and 2.752 A). The magnetic AC susceptibility data show that in spite of the absence of zero-field splitting in the Cu(II) ion with S = 1/2, the compound demonstrates a slow magnetic relaxation behaviour at a weak applied magnetic field (HDC = 500 Oe). The EPR spectra and DC magnetic measurements show the strong axial anisotropy of the g-tensor. The temperature dependence of the relaxation time is well described by the combination of one-phonon direct and two-phonon Raman processes.

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 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.

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.

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.

Annealing of a (Pr0.53Dy0.47)12(Fe0.77Co0.23)80B8 (at %) alloy is found to affect the magnetic properties of the sintered magnets fabricated from the alloy. Annealing of the alloy is shown to lead to a 8% increase in the remanence and to nonmonotonic variations of the coercive force by 10–12%. The detected 4% decrease in the dysprosium content in the main magnetic phase and 1% increase in the phase content in the sintered magnet can favor an increase in the residual magnetization. Annealing of the alloy does not lead to changes in the temperature coefficient of induction of the sintered magnets. The diffusion of dysprosium is the most probable cause for the detected changes.

Magnetic and structural characteristics of the main phases contained in the Nd−Dy−Fe−Co−B magnetically hard materials (in particular, (Nd0.33Dy0.67)1(Fe0.60Co0.40)4.74B1.12 and (Nd0.90Dy0.10)(Fe0.61Co0.39)3.13 intermetallic compounds) are studied. Parameters of unit cells, saturation magnetizations at 80 and 350 K, and the temperature dependence of the magnetization in the presence of a field of 800 kA/m at temperatures ranging from 320 to 600 K are analyzed. It is shown that the above compounds provide 10–15% contribution to the magnetization of the Nd–Dy–Fe–Co–B sintered magnets even at relatively low concentrations of up to 20%. The results can be used to separate contributions of the main and secondary phases in sintered magnets with different compositions.

The time changes in the magnetization of the magnets (Pr0.51Dy0.49)13(Fe0.64Co0.36)80B7 and (Pr0.51Dy0.49)13(Fe0.64Co0.36)79Cu1B7 (at %) sintered at 160°C are studied. Alloying of the Pr–Dy–Fe–Co–B materials with copper is shown to cause a decrease in the magnetization losses in time.

A new binuclear μ-NSC-type nitrosyl iron complex [Fe2(SR)2(NO)4] (R is 5-phenyl-1H-1,2,4-triazole-3-thiolyl) was synthesized. The composition and structure of the newly synthesized complex were determined by atomic absorption, IR, EPR, and Mossbauer spectroscopy and SQUID magnetometry. Amperometric analysis showed that the new complex is an effective nitric oxide (NO) donor in a 1% aqueous DMSO solution. The amounts of NO generated by the complex [Fe2(SR)2(NO)4] in aqueous solutions at physiological pH values were determined. The new complex was shown to have higher antibacterial activity against the gram-positive bacteria Micrococcus luteus compared to kanamycin and streptomycin. According to assays, sulfur-containing ligands of the 1,2,4-triazole-3-thiol series are promising for the design of new antibacterial agents containing the {Fe(NO)2} structural moiety.

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.

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.

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.

Reactions of [Mn(H2 dapsc)Cl2 ]⋅H2 O (dapsc=2,6- diacetylpyridine bis(semicarbazone)) with K3 [Fe(CN)6 ] and (PPh4 )3 [Fe(CN)6 ] lead to the formation of the chain polymeric complex {[Mn(H2 dapsc)][Fe(CN)6 ][K(H2 O)3.5 ]}n ⋅1.5n H2 O (1) and the discrete pentanuclear complex {[Mn(H2 dapsc)]3 [Fe(CN)6 ]2 (H2 O)2 }⋅4 CH3 OH⋅3.4 H2 O (2), respectively. In the crystal structure of 1 the high-spin [MnII (H2 dapsc)]2+ cations and low-spin hexacyanoferrate(III) anions are assembled into alternating heterometallic cyano-bridged chains. The K+ ions are located between the chains and are coordinated by oxygen atoms of the H2 dapsc ligand and water molecules. The magnetic structure of 1 is built from ferrimagnetic chains, which are antiferromagnetically coupled. The complex exhibits metamagnetism and frequency-dependent ac magnetic susceptibility, indicating single-chain magnetic behavior with a Mydosh-parameter φ=0.12 and an effective energy barrier (Ueff /kB ) of 36.0 K with τ0 =2.34×10-11 s for the spin relaxation. Detailed theoretical analysis showed highly anisotropic intra-chain spin coupling between [FeIII (CN)6 ]3- and [MnII (H2 dapsc)]2+ units resulting from orbital degeneracy and unquenched orbital momentum of [FeIII (CN)6 ]3- complexes. The origin of the metamagnetic transition is discussed in terms of strong magnetic anisotropy and weak AF interchain spin coupling.

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.

—Changes in the magnetic properties of the sintered (Pr0.76Dy0.24)12.9(Fe0.53Co0.47)81.5B5.6 material, which are caused by solid-phase alloying with the (Pr0.63Dy0.37)(Fe0.31Co0.69)2B2 alloy are studied. The dependences of the phase composition and the coercive force of the sintered material on the amount of the added alloy is obtained. As the boron content in the sintered material increases, the content of the main magnetic (Pr, Dy)2(Fe, Co)14B phase decreases from 89.2 to 51.4 vol % and the content of the (Pr, Dy)(Fe, Co)3 phase increases from 7.1 to 43.9 vol %. It was found that, in the course of 190-h storage of sintered magnets in air, their coercive force and density are first unchanged and subsequently decrease; the coercive force decreases to zero.

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.

—The problem of destruction of blanks of ring Nd–Dy–Fe–Co–B magnets with a radial texture and different cobalt and dysprosium contents is considered. The cause of the failure of radial rings after sintering consists in the presence of the (Nd, Dy)(Fe,Co)4B phase, which is characterized by a high linear thermal expansion coefficient. It is shown that the contribution of the (Nd, Dy)(Fe, Co)4B phase to the saturation magnetization can be neglected. The identified phase is found to have a compensation temperature of 100 K.

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.

The effect of copper alloying on the coercive force and the residual induction of sintered materials (Pr0.53Dy0.47)13(Fe0.64Co0.36)resCuxB6 (x = 0–3 at %) annealed at various temperatures is considered. The dependences of coercive force HcI and residual induction Br on the copper content are found to be nonmonotonic. This fact is explained by that alloying with copper leads to a change in the phase composition, which is accompanied by an increase in the coercive force and the residual magnetization of the alloy, while a change in the chemical composition and the thickness of intergranular interlayers upon copper alloying leads to a decrease in the values of HcI and Br as the copper content increases.

New method for the synthesis of the mononuclear anionic iron dinitrosyl complexes (DNICs) as prospective agents for nitric oxide (NO) chemotherapy of oncological diseases has been developed. Mononuclear anionic DNIC of the composition (N2H5)+[Fe(SR)2(NO)2]- with R = 5-nitropyridinyl (I) has been synthesized by the reaction of aqueous solutions of Na2[Fе(S2O3)2(NO)2] and N2H5[SС5H3N2O2] salts. The latter one was synthesized by the reduction of bis-(5-nitro-pyridin-2-yl) disulfide with hydrazine hydrate in ethanol at T = 25 °C. Physical-chemical properties of the synthesized complex were studied by X-ray, SEM, IR-, EPR, Mossbauer spectroscopy and SQUID magnetometry in combination with DFT quantum-chemical calculation of molecular structure and spectroscopic properties. Complex I was found to generate NO in proton media without additional activation. The cytotoxicity of I to human tumor cells of various geneses, viz. ovarian cancer SKOV3, colon cancer LS174T and non-small cell lung cancer A549 was discovered for the first time.

Sintered (Pr0.53Dy0.47)ΣR(Fe0.77Co0.23)balB7.5 materials are studied. For the Nd–Fe–B-based materials, the calculated neodymium content in the Nd2Fe14B compound is 11.8 at %, whereas an excess neodymium content as compared to that for the stoichiometric composition should be taken for manufacturing magnets. In contrast to the magnets based on the aforementioned system, the magnets based on the Pr–Dy–Fe–Co–B system can be prepared at a lower total rare-earth metal content as compared to that corresponding to the stoichiometric composition. Magnets with a coercive force of 528 kA/m are manufactured at a total rare-earth metal content of 11.5 at %, which is lower than that calculated for the R2(Fe, Co)14B (R = Pr, Dy) phase.

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.

The magnetocrystalline anisotropy of uniaxial (PrDy)(FeCo)B rare-earth magnets is determined using the Akulov model and studied in the 2–300 K temperature. The (PrDy)(FeCo)B samples demonstrate the power dependence of anisotropy constant K(T) on saturation magnetization MS(T) in the temperature range 2–300 K with exponents m = 1.7–2.1, according to the empiric Callen–Callen rule. A deviation of power dependence K( $$M_{S}^{m}$$ ) is observed in the samples with the Gd impurity. Possible causes of the deviation from the Callen–Callen rule and variations of exponent m are discussed.

The relationship of the micromagnetic structure, the contributions of various crystalline phases and hysterons obtained by the first order reversal curves (FORC) method in sintered (NdDy)(FeCo)B magnets is discussed. The distribution map of parameters of magnetic hysteresis partial loops that allows the separation of various spin ensembles to the magnetization has been built.