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Recent experimental observation of inertial spin dynamics calls upon holistic reevaluation of the theoretical framework of magnetic resonance in ferromagnets. Here, we derive the secular equation of an inertial spin system in analogy to the ubiquitous Smit-Beljers formalism. We find that the frequency of precessional ferromagnetic resonances is decreased as compared to the noninertial case. We also find that the frequency of nutational resonances is generally increased due to the presence of magnetic anisotropy and applied magnetic field. We obtain exact solutions of the secular equation and approximations that employ the terminology of noninertial theory and thus allow for convenient estimates of the inertial effects.

The effects of hydrogen absorption on the effective magnetization $(4\ensuremath{\pi}{M}_{\mathrm{eff}})$, gyromagnetic ratio $(\ensuremath{\gamma})$, Gilbert damping constant $({\ensuremath{\alpha}}_{\mathrm{G}})$, and the inhomogeneous linewidth broadening $(\mathrm{\ensuremath{\Delta}}{H}_{0})$ in $\mathrm{Py}(x)/\mathrm{Y}$(16 nm)/Pd(15 nm) trilayer films ($x=2$, 3, 5, 8, 10, 20, 40 nm) were investigated with ferromagnetic resonance (FMR), transmission electron microscopy, and vibrating sample magnetometry. In the presence of a hydrogen atmosphere, the samples show a reduction of their FMR linewidth which is found to stem purely from a reduction of the inhomogeneous linewidth broadening. This is attributed to a rearrangement of atoms at the Py/Y interface in the presence of hydrogen, making the Py/Y interface more homogeneous. In addition, a reduction of $4\ensuremath{\pi}{M}_{\mathrm{eff}}$ was seen for all samples in the hydrogen atmosphere which is typical for an increase of the interfacial perpendicular magnetic anisotropy at the Py/Y interface.

We report on ferromagnetic resonance (FMR) detected spin pumping in Fe60Al40 /Pd and Py/Fe60Al40 bilayers, and laterally patterned Fe60Al40 (FeAl) nanostructures. The magnetic properties of FeAl alloy are tailorable from paramagnetic to ferromagnetic state by variation of the structure through an ion beam irradiation, which makes this material promising for the fabrication of magnetic landscapes and magnonic crystals. Exploiting this tunability, we show that FeAl can be used as spin source and spin sink in spin pumping experiments. Using the material with the identical chemical composition as para- and ferromagnet, we suggest a new pathway for creating lateral spin pumping geometries which are produced with ion beam irradiation of B2 alloys.

The L10 crystal structure underlines an important class of chemically ordered alloys that exhibits uniaxial magnetocrystalline anisotropy. The near-equiatomic L10-FeNi extracted from meteorites has demonstrated intriguing magnetic properties for permanent magnet applications. However, the synthesis of this chemically ordered non-cubic structure has been a longstanding challenge. Here, we demonstrate the absence of cubic symmetry in near-equiatomic Fe-Ni nanoparticles synthesized by picosecond-pulsed laser ablation in liquids. The non-cubic phase detected in these particles can only be L10-FeNi or hexagonal close-packed (HCP) FeNi, and the absence of cubic symmetry was unequivocal. The orientation relationship between the non-cubic phase and the adjacent cubic phase was characterized by a series of transmission electron microscopy (TEM) techniques, which consistently suggests that the formation of the non-cubic phase involves a martensitic transformation process.

Dendrimers are perfect tree-like radially symmetric macromolecules with regular branching. Due to their architecture, dendrimers possess a set of unique properties, including high penetrating ability and a large number of functionalizable terminal groups. Practical use of dendrimers as delivery agents or nanoreactors in many cases involves a free space in a dendrimer interior. The question about presence of a hollow core (a cavity) inside the dendrimer molecule placed in a solvent attracts interest of researchers since the discovery of dendrimers. This review presents a rigorous discussion on the dendrimer structure in solution. The main objective is to draw attention to the difference in the structure of homopolymer and copolymer dendrimers. Theoretical studies typically consider homopolymer dendrimers (with similar inner and terminal segments), whereas experiments often examine dendrimers with massive terminal groups which chemical structure is different from the structure of the dendrimer inner groups. In the latter case, dendrimer is a copolymer macromolecule, and its conformation can depend on additional factors, such as solvent selectivity, or poor compatibility of terminal and core groups. The influence of these factors can lead to the formation of a region with a lower polymer density inside the dendrimer.

Inertia effects in magnetization dynamics are theoretically shown to result in a different type of spin waves, i.e. nutation surface spin waves, which propagate at terahertz frequencies in in-plane magnetized ferromagnetic thin films. Considering the magnetostatic limit, i.e. neglecting exchange coupling, we calculate dispersion relation and group velocity, which we find to be slower than the velocity of conventional (precession) spin waves. In addition, we find that the nutation surface spin waves are backward spin waves. Furthermore, we show that inertia causes a decrease of the frequency of the precession spin waves, namely magnetostatic surface spin waves and backward volume magnetostatic spin waves. The magnitude of the decrease depends on the magnetic properties of the film and its geometry., Comment: 9 pages, 4 figures

The results of a comprehensive study of structural, magnetic and magneto-optical properties of 10–262 nm thick Zn 1-x Co x O y films ( x = 0–0.3) grown on c -sapphire substrates by pulsed laser deposition (PLD) method are present. It is revealed that all of the synthesized Zn 1-x Co x O y films possess a wurtzite structure with the following lattice parameters: a = 3.2495 A, c = 5.2329–5.2485 A. It is detected that ferromagnetic properties of Zn 1-x Co x O y films at room temperature vary non-monotonically with the increase of Co concentration. The strongest ferromagnetic signal is observed in the Zn 0.87 Co 0.13 O y film due to the largest number of metallic Co clusters formed in the sample. A further increase of dopant concentrations in the films leads to the oxidation of metallic Co and the development of the paramagnetic Co 3 O 4 phase which result in the decrease of the ferromagnetic signal. It is determined that specific magnetic characteristics of Zn 1-x Co x O y samples do not depend on the film thickness. Characteristics of transversal Kerr effect pertaining to cobalt concentration in Zn 1-x Co x O y films as well as thickness of the samples are studied for the first time. The correlation between the amplitude of the magneto-optical signal and the magnetization value of the films is established.

The understanding of how spins move and can be manipulated at pico- and femtosecond timescales has implications for ultrafast and energy-efficient data-processing and storage applications. However, the possibility of realizing commercial technologies based on ultrafast spin dynamics has been hampered by our limited knowledge of the physics behind processes on this timescale. Recently, it has been suggested that inertial effects should be considered in the full description of the spin dynamics at these ultrafast timescales, but a clear observation of such effects in ferromagnets is still lacking. Here, we report direct experimental evidence of intrinsic inertial spin dynamics in ferromagnetic thin films in the form of a nutation of the magnetization at a frequency of ~0.5 THz. This allows us to reveal that the angular momentum relaxation time in ferromagnets is on the order of 10 ps. Inertial dynamics are observed in a ferromagnet. Specifically, a nutation is seen on top of the usual spin precession that has a lifetime on the order of 10 picoseconds.

Skyrmions and antiskyrmions are topologically protected spin structures with opposite vorticities. Particularly in coexisting phases, these two types of magnetic quasi-particles may show fascinating physics and potential for spintronic devices. While skyrmions are observed in a wide range of materials, until now antiskyrmions were exclusive to materials with D2d symmetry. In this work, we show first and second-order antiskyrmions stabilized by magnetic dipole–dipole interaction in Fe/Gd-based multilayers. We modify the magnetic properties of the multilayers by Ir insertion layers. Using Lorentz transmission electron microscopy imaging, we observe coexisting antiskyrmions, Bloch skyrmions, and type-2 bubbles and determine the range of material properties and magnetic fields where the different spin objects form and dissipate. We perform micromagnetic simulations to obtain more insight into the studied system and conclude that the reduction of saturation magnetization and uniaxial magnetic anisotropy leads to the existence of this zoo of different spin objects and that they are primarily stabilized by dipolar interaction. Antiskyrmions are topological spin textures with negative vorticity. Like skyrmions, they have considerable technological promise, but have only been stabilised in Heusler compounds. Here, Heigl et al. succeed in stabilising first and second order antiskyrmions in a new class of materials.

The inertial dynamics of magnetization in a ferromagnet is investigated theoretically. The analytically derived dynamic response upon microwave excitation shows two peaks: ferromagnetic and nutation resonances. The exact analytical expressions of frequency and linewidth of the magnetic nutation resonance are deduced from the frequency dependent susceptibility determined by the inertial Landau-Lifshitz-Gilbert equation. The study shows that the dependence of nutation linewidth on the Gilbert precession damping has a minimum, which becomes more expressive with increase of the applied magnetic field.

Journal of sol gel science and technology 81(2), 327 - 332 (2017). doi:10.1007/s10971-016-4254-2, Iron nanowires with the diameter of ca. 40 nm and a length up to few dozens of microns are fabricated via templated electrodeposition using anodic aluminum oxide (AAO) film as porous matrix. Despite polycrystalline structure of wires the technique allows fabrication of dense deposits with micrometer-sized single crystalline grains within AAO templates and high chemical stability towards oxidation. Nanowire arrays exhibit strong magnetization anisotropy with saturation magnetization of 180 emu/g and coercive field of 815 Oe in direction parallel to the long axis of nanowires and 230 Oe in perpendicular direction. The effective hyperfine fields on iron atoms as extracted from Mossbauer and Nuclear Forward Scattering of sample in demagnetized state indicates slight deviation of magnetization vector (~ 6°) from nanowire long axis appearing probably due to curling of magnetic moments by antisymmetric exchange interactions at the surface of nanowires., Published by Springer Science + Business Media B.V, Dordrecht [u.a.]

The magnetic and magnetocaloric properties of the LuFe2–x Mn x O4 + δ (x = 0, 0.05, 0.12) system have been studied. A partial substitution of manganese for iron leads to a noticeable decrease in the magnetization and the magnetocaloric effect. It has been shown that the magnetocaloric effect in LuFe2–x Mn x O4 + δ samples is determined by several mechanisms.

The structural, transport, and magnetic characteristics of polycrystalline Mn x Si1–x (x ≈ 0.51–0.52) films grown by pulsed laser deposition onto Al2O3(0001) substrates when the low-energy components are deposited owing to collisions with the atoms of the buffer gas have been studied in the “shadow” geometry. The magnetization of these films is determined by two ferromagnetic phases—the high-temperature phase with the Curie temperature T C ≈ 370 K and the low-temperature one with T C ≈ 46 K. The anomalous Hall effect changes sign from positive to negative with a decrease in temperature. The sign change occurs in the temperature range of 30–50 K; the specific value of this temperature depends on the thickness of the Mn x Si1–x film. The results can be interpreted in terms of the structural self-organization related to the formation of two layers in the course of film growth. These layers have nearly the same chemical composition but significantly differ in the shapes and sizes of crystallites. This leads to a drastic difference in the values of T C and in the value and the sign of the anomalous Hall effect for such layers.

In the emerging field of magnonics, spin waves are foreseen as signal carriers for future spintronic information processing and communication devices, owing to both the very low power losses and a high device miniaturisation potential predicted for short-wavelength spin waves. Yet, the efficient excitation and controlled propagation of nanoscale spin waves remains a severe challenge. Here, we report the observation of high-amplitude, ultrashort dipole-exchange spin waves (down to 80 nm wavelength at 10 GHz frequency) in a ferromagnetic single layer system, coherently excited by the driven dynamics of a spin vortex core. We used time-resolved x-ray microscopy to directly image such propagating spin waves and their excitation over a wide range of frequencies. By further analysis, we found that these waves exhibit a heterosymmetric mode profile, involving regions with anti-Larmor precession sense and purely linear magnetic oscillation. In particular, this mode profile consists of dynamic vortices with laterally alternating helicity, leading to a partial magnetic flux closure over the film thickness, which is explained by a strong and unexpected mode hybridisation. This spin-wave phenomenon observed is a general effect inherent to the dynamics of sufficiently thick ferromagnetic single layer films, independent of the specific excitation method employed.

Barium hexaferrite pellets were prepared by sintering method and single crystal was obtained by flux technique. The thermal expansion coefficients of Ba 0,3 Pb 0,7 Fe 12 O 19 single crystal along a and c axes are 9.9 * 10 –6 K –1 and 17.4 * 10 –6 K –1 . It is in a good agreement with thermal expansion coefficients of pellets. The complicated expansion curve along a axe at 400–780 °C could originate from magnetic disordering near Curie temperature.

In the attempt of implementing iron garnets with perpendicular magnetic anisotropy (PMA) in spintronics, the attention turned towards strain-grown iron garnets. One candidate is Tm3Fe5O12 (TmIG) which possesses an out-of-plane magnetic easy axis when grown under tensile strain. In this study, the effect of film thickness on the structural and magnetic properties of TmIG films including magnetic anisotropy, saturation magnetization, and Gilbert damping is investigated. TmIG films with thicknesses between 20 and 300 nm are epitaxially grown by pulsed laser deposition on substituted-Gd3Ga5O12(111) substrates. Structural characterization shows that films thinner than 200 nm show in-plane tensile strain, thus exhibiting PMA due to strain-induced magnetoelastic anisotropy. However, with increasing film thickness a relaxation of the unit cell is observed resulting in the rotation of the magnetic easy axis towards the sample plane due to the dominant shape anisotropy. Furthermore, the Gilbert damping parameter is found to be in the range of 0.02 ± 0.005.

Ferromagnetic resonance of a thin film alloy has been tuned by inducing lateral interfaces between layers differing in their lattice ordering and magnetic properties. By disordering B2 Fe60Al40 thin films to the A2 structure, thereby manifesting planar A2/B2 interfaces at selected depths, we show that the resonance lines at 10 GHz are shifted by 284 mT and 35 mT for fields applied perpendicular-to-plane and in-plane, respectively. The resonance line shift occurs over a broad frequency range and is driven by strain relaxation due to the increasing magnetic layer thickness. A finer anomalous line shift occurs as the A2/B2 interface approaches the film/substrate interface prior to being expelled from the film. The A2 structure can be reannealed to the B2 order, implying that disorder/order interface modification can provide a path for reversibly encoding resonant properties in alloy thin films.

Two different types of fluxes, namely sodium based and chloride based fluxes were used to grow Cr substituted barium and strontium hexaferrite ferrite crystals, (Sr,Ba)Fe 12 − x Cr x O 19 at comparatively low temperatures of about 1300 °C. The sodium based flux led to growth of larger crystals up to 5 mm, but with only minor Cr contents x ≤ 0.07. From the chloride based flux the obtained Cr contents are significantly higher with x = 5.7 (Sr) and x = 3.4 (Ba), however, crystals reach only sizes in the sub-mm range. X-ray absorption spectroscopy data support exclusively isovalent substitution of Fe 3+ by Cr 3+ even for very low Cr contents. 57 Fe Mosbauer spectroscopy reveals Cr to preferentially occupy the six-fold by oxygen coordinated site at 12 k and, to a lower degree, 2 a and 4 f 2 in space group P 6 3 / mmc . All characteristic magnetic properties drop upon Cr substitution, e. g., the Curie temperature from 728 K for pure BaFe 12 O 19 to 465 K for BaFe 8.6 Cr 3.4 O 19 , the saturation magnetization from 71 emu/g to 29.7 emu/g and the coercive field from 363 Oe to 45 Oe.

Magnetoplumbite type barium ferrite single crystals BaFe 12− x Cu x O 19 with various Cu-contents in the range of x ≤0.032 with edge-length of up to 12 mm were obtained from carbonate flux at 1260 °C. The unit cell parameters of obtained crystals increase slightly with Cu-concentration. Saturation magnetization, Curie temperature and coercivity of BaFe 12− x Cu x O 19 drop with Cu-content, particularly above about x =0.02. The change in H c is only insignificant.

Zn-doped barium hexaferrite BaFe12−xZnxO19 (0 ≤ x ≤ 0.065) single crystals were grown from carbonate flux at temperatures below 1260 °C in order to study the effect of Zn-substitution on the structural and magnetic properties. Upon increasing Zn-content the lattice parameters increase to a small degree, due to a larger ionic size of Zn2+ as compared to Fe3+. The saturation magnetization and coercivity of the studied crystals turns out to depend very sensitive on the level of Zn-substitution. A considerable coercivity decrease up to 30% was observed for samples with x = 0.065, while the Curie temperature was found to be comparably little influenced, dropping from 455 °C for the undoped compound to 445 °C for the maximum x obtained. We demonstrate the possibility to use the carbonate flux growth method for producing hexaferrite crystals and tune their functional properties via doping with zinc.

In this report, were studied the heating capability of magnetic nanoparticles (MNps) made from Zn-substituted manganese ferrite compounds ZnxMn1-xFe2O4 with Zn content varying from 0% to 90%. The MNps of diameter 5-25 nm were synthesized by co-precipitation of metal salt solution with NaOH solution. It was shown, that specific absorption rate (SAR) for the compound with Zn content of 20% is bigger than the other ones exhibited 1.5 W/g. Also SAR for the magnetic liquids made of the MNps shows bigger SAR values, which indicates the Brown relaxation mechanism in the system.

The paper reports on the comprehensive study of properties of nonstoichiometric Si1−xMnx alloys slightly enriched in Mn (x≈0.51–0.55) as compared to the stoichiometric monosilicide MnSi. Mosaic type Si1−xMnx films 55–70 nm in thickness were produced by the pulsed laser deposition (PLD) method onto the single crystalline Al2O3 substrates at 340 °C. The Curie temperature TC in nonstoichiometric Si1−xMnx (x≈0.52–0.55) films exceeds room temperature, while in their stoichiometric counterpart, MnSi, the TC value does not exceed ≈30 К. The consistent data on anomalous Hall effect and transverse Kerr effect prove the global character of ferromagnetic (FM) order caused by magnetic defect formation rather than the presence of FM clusters. Аt Mn content x≤0.55, the magnetization data testify to a good homogeneity in the distribution of magnetic defects without their segregation: variations of the saturation magnetization Ms do not exceed 6% in the temperature range T=10–100 К and are well described by the Bloch law. It is also revealed that textured high-quality Si1−xMnx films with x≈0.52 and ТС~300 К could be formed by PLD method in the “shadow” geometry (at lower energy of deposited atoms).

We present the results of numerical simulation of magnetodielectric effect (MDE) in magnetorheological elastomers (MRE)&mdash, the change of effective permittivity of elastomer placed under the external magnetic field. The computer model of effect is based on an assumption about the displacement of magnetic particles inside the elastic matrix under the external magnetic field and the formation of chain-like structures. Such displacement of metallic particles between the planes of capacitor leads to the change of capacity, which can be considered as a change of effective permittivity of elastomer caused by magnetic field (magnetodielectric effect). In the literature, mainly the 2D approach is used to model similar effects. In this paper, we present a new approach of magnetorheological elastomers simulation&mdash, a 3D-model of the magnetodielectric effect with ability to simulate systems of 10 5 particles. Within the framework of the model, three types of particle size distributions were simulated, which gives an advantage over previously reported approaches. Lognormal size distribution was shown to give better qualitative match of the modeling and experimental results than monosized type. The developed model resulted in a good qualitative agreement with all experimental data obtained earlier for Fe-based elastomers. The proposed model is useful to study these novel functional materials, analyze the features of magnetodielectric effect and predict the optimal composition of magnetorheological elastomers for further profound experimental study.

Performance combined with simplicity: we demonstrate that thick Permalloy films exhibiting a weak growth-induced perpendicular magnetic anisotropy can be employed as an ideal test system for the study of magnetodynamical processes in perpendicularly magnetized systems exhibiting magnetic textures ranging from isolated magnetic bubbles to more complex n"pi" states.

Elucidating the interaction between magnetic moments and itinerant carriers is an important step to spintronic applications. Here, we investigate magnetic and transport properties in d0 ferromagnetic SiC single crystals prepared by postimplantation pulsed laser annealing. Magnetic moments are contributed by the p states of carbon atoms, but their magnetic circular dichroism is different from that in semi-insulating SiC samples. The anomalous Hall effect and negative magnetoresistance indicate the influence of d0 spin order on free carriers. The ferromagnetism is relatively weak in N-implanted SiC compared with that in Al-implanted SiC after annealing. The results suggest that d0 magnetic moments and itinerant carriers can interact with each other, which will facilitate the development of SiC spintronic devices with d0 ferromagnetism., 20 pages, 5 figures

Large single crystals with sizes of up to 15 mm of cobalt and nickel-substituted M-type barium hexaferrite BaFe12−xMxO19 (M = Ni, Co) were obtained from carbonate flux at temperatures as low as 1260 °C. The Co and Ni contents in the crystals can be controlled via the content in the flux, but is restricted to about x ⩽ 0.3. An increasing amount of the substitution results in a monotonous reduction of the Curie temperature, the saturation magnetization at room temperature and the coercive force.

We report recent experimental results on the mag- netic, magnetotransport, and magneto-optical properties of Co- and V-doped TiO2−δ magnetic oxides at the doping level around 1 at. %. The samples were prepared using rf magnetron sputtering in identical conditions that allows to compare the mechanisms of above-room-temperature ferro- magnetism observed in both cases of doping. In spite of the comparable values of magnetic moment around 1 ÷ 2.5 µB per 3d impurity derived from macroscopic magnetic mea- surements for both systems, the magneto-optical response

Ti-substituted barium hexaferrite BaFe12O19 single crystals BaFe12–xTixO19 with x up to 1.3 and sizes 2–8 mm were grown by spontaneous crystallization from molten sodium carbonate flux. The distribution of Ti on different crystallographic sites was determined from single crystal X-ray diffraction data. For low Ti contents up to x = 0.8 the unit cell expands; on further increase of the Ti amount the unit cell starts to shrink. This behavior for low Ti contents is most likely due to a reduction of Fe3+ to Fe2+ for charge balance. At higher Ti concentrations, supposedly vacancies in the transition metal substructure are formed. An increasing Ti concentration results in a monotonous reduction of the Curie temperature from 452 to 251 °C and the saturation magnetization at room temperature from 64.8 to 24.8 emu/g for powder samples and from 70.0 to 60.1 emu/g for single crystals (for x up to 0.78).

The study is concerned with the structural, optical, magnetic, and transport properties of Zn1 − xCoxO (x = 0.05–0.45) films produced on Al2O3 (0001) substrates at a temperature of Ts = 500°C by pulsed laser deposition with fast particle separation. The film thickness is d = 60–300 nm. It is found that the Zn1 − xCoxO ternary alloy retains its wurtzite-type crystal structure up to x = 0.35, if the films are produced at low buffer-oxygen pressures (∼10−6 Torr). It is established that, in these conditions, the electron concentration is higher than 1020 cm−3 because of the high density of oxygen donor vacancies. In this case, the films start to exhibit ferromagnetism in the magnetization and the anomalous Hall effect at temperatures above 100 K. The sign of the anomalous Hall effect is found to be positive and opposite to the sign of the normal Hall effect, as occurs in Co metal layers. This is indicative of the cluster nature of ferromagnetism of the Zn1 − xCoxO films. For thin Zn1 − xCoxO layers (d = 60 nm, x = 0.2) in a transverse magnetic field, profound hysteresis of the magnetoresistance is observed, which is indicative of the out-of-plain easy axis of magnetization of the films. The magnetic anisotropy is attributed to the structuring of the layers (elongation of magnetic clusters along the growth axis of the films). The structuring can lead to noticeable strengthening of the layer ferromagnetism.

Magnetically ordered γ-Fe2O3 was obtained by the interaction of Fe(NH4)2(SO4)2 and NaH2PO2 in aerated aqueous alkaline solution in the presence of 2-hydroxypropyl-β-cyclodextrin at room temperature; the only crystal phase (maghemite) was detected in the sample.

Магнитоактивный эластомер – новый тип магнитоуправляемых материалов, свойства которых обратимо изменяются под действием магнитного поля. Данный материал относится к классу Smart materials. Одним из свойств материала является магнитореологический эффект, т.е зависимость вязкоупругих свойств от магнитного поля. На самом деле материал обладает большим набором разных свойств. Подробное исследование материала выявило в нем наличие совокупности свойств: магнитореологический эффект, магнитодеформационный эффект, магнитострикционный эффект, эффект памяти формы (эффект псевдопластичности), магниторезистивный эффект, магнитопьезорезистивный эффект. Такие параметры, как диэлектрическая проницаемость и магнитная восприимчивость, также изменяются под действием магнитного поля. Многообразные свойства материала определяются процессами диполь-дипольного взаимодействия между намагниченными частицами магнитного наполнителя, а также процессами обратимого перемещения (структурирования) или вращения анизотропных частиц наполнителя внутри полимерной матрицы. Области применения материала – эффективные пассивные и активные управляемые демпфирующие устройства, датчики магнитного поля, ускорения, давления, деформации, а также биологии – клеточных технологий.

Programmability of stable magnetization configurations in a magnetic device is a highly desirable feature for a variety of applications, such as in magneto-transport and spin-wave logic. Periodic systems such as antidot lattices may exhibit programmability; however, to achieve multiple stable magnetization configurations the lattice geometry must be optimized. We consider the magnetization states in Co-antidot lattices of ≈ 50 nm thickness and ≈ 150 nm inter-antidot distance. Micromagnetic simulations were applied to investigate the magnetization states around individual antidots during the reversal process. The reversal processes predicted by micromagnetics were confirmed by experimental observations. Magnetization reversal in these antidots occurs via field driven transition between 3 elementary magnetization states – termed G, C and Q. These magnetization states can be described by vectors, and the reversal process proceeds via step-wise linear operations on these vector states. Rules governing the co-existence of the three magnetization states were empirically observed. It is shown that in an n × n antidot lattice, a variety of field switchable combinations of G, C and Q can occur, indicating programmability of the antidot lattices.

The transport and magnetic properties of Si1 − x Mn x films of thickness 55–70 nm with various Mn content (x = 0.44–0.6) are studied in the temperature range of 5–400 K and in magnetic fields up to 2 T. The films are grown by pulsed laser deposition on Al2O3 (0001) substrates at a temperature of 340°C using velocity separation of deposited particles. The films exhibit metal conductivity and the resistivity ρ = (2−8) × 10−4 Ω cm, typical of highly degenerate semiconductors. It is found that the anomalous component of the Hall effect dominates over the normal component at T = 300 K for the Si1 − x Mn x alloy with x ≈ 0.5, and that the Curie temperature significantly exceeds room temperature and is estimated as ∼500 K from magnetization measurements (for MnSi silicide the Curie temperature is T C = 30 K). It is shown that the anomalous component of the Hall conductivity at low temperatures is controlled by “side-jump” and (or) “intrinsic” mechanisms independent on the carrier scattering time. The results are explained by features of the formation of defects with localized magnetic moments in the case of Si1 − x Mn x films with x ≈ 0.5 and by the significant role of matrix spin fluctuations in the exchange between these defects.

The state and outlook of works on the creation of ferromagnetic semiconductor materials for applications in spin electronics and informatics units are considered. The obtained results on promising ferromagnetic semiconductor material classes—doped elementary semiconductors, AIIIBV compounds, and semiconductor oxides—are given. Unsolved problems in the considered area are indicated and possible ways of their solutions are outlined.

It has been found that the Curie temperature (T C ≈ 300 K) in nonstoichiometric Si1 − x Mn x alloys slightly enriched in Mn (x ≈ 0.52–0.55) in comparison to the stoichiometric manganese monosilicide MnSi becomes about an order of magnitude higher than that in MnSi (T C ∼ 30 K). Deviations from stoichiometry lead to a drastic decrease in the density of charge carries (holes), whereas their mobility at about 100 K becomes an order of magnitude higher than the value characteristic of MnSi. The high-temperature ferromagnetism is ascribed to the formation of defects with the localized magnetic moments and by their indirect exchange interaction mediated by the paramagnetic fluctuations of the hole spin density. The existence of defects with the localized magnetic moments in Si1 − x Mn x alloys with x ≈ 0.52–0.55 is supported by the results of numerical calculations performed within the framework of the local-density-functional approximation. The increase in the hole mobility in the nonstoichiometric material is attributed to the decay of the Kondo (or spin-polaron) resonances presumably existing in MnSi.

The effect of micro-and nanocrystalline structural state on magnetic properties and magnetic entropy (ΔSM) of Gd is investigated. The marked influence of severe plastic deformation on ΔSM is demonstrated.

The magnetic properties of small 4d, 5d metal nanoparticles of Pd, Pt (clusters) are attracting a great attention because these materials in bulk are paramagnetic. In this work we report the ferromagnetic-like behavior of the small Pt nanoparticles prepared by chemical method. Highly dispersed Pt clusters have been synthesized on the surfaces of a porous spherical γ-Al2O3 particles. The process of the chemical deposition of metalorganic fluid with employment of the supercritical fluid was used. The samples of the Pt/γ-Al2O3 nanoparticles have been prepared in INEOS RAS. The nanoparticles size distribution was determined by small-angle X-rays scattering (SAXS). It was found that the Pt clusters have a bimodal particle size distribution with two peaks: R1max=20 Å and R2max=40 Å. The magnetic properties of the clusters have been investigated, using VSM magnetometer, in magnetic field up to ±3 kOe and at a temperature range from 80 to 400 K. It was observed that Pt/γ-Al2O3 nanoparticles show the ferromagnetic-like behavior in whole specified temperature range, the value of coercivity decreases gradually from 130 Oe to 80 Oe. The origin of ferromagnetic-like behavior of the Pt/γ-Al2O3 nanoparticles is discussed.

Magnetic and magnetooptical properties of the Cr-doped GaN layers have been investigated in the temperature range 50–400 K. A high saturation magnetization of 25 G has been observed in the obtained material. Spectra of the magnetooptical transversal Kerr effect have revealed strong magnetic response in the energy range less than 3.0 eV due to the appearance of new spin-polarization states in the band gap of GaN upon Cr doping.

In this chapter, we will survey early and recent experimental results on magnetic properties of dilute magnetic oxide semiconductors, focusing on TiO2-δ:Co and TiO2-δ:V. Room temperature ferromagnetism was observed in both types of thin film samples fabricated by RF sputtering, but their magnetic properties appeared to be quite different. Magnetic moments in case of TiO2-δ:Co are mostly associated with local polarization of Co ions and induced defects. There is an evidence of intrinsic ferromagnetism in the case of low Co content (

The effect of parabenzoquinone molecule adsorption on the magnetic properties of nanostructured silicon is studied. A mesoporous silicon sample with a specific surface area of ∼ 800 m2/g was used as nanostructured silicon. It is found that parabenzoquinone molecule adsorption on a porous silicon surface results in the formation of a new nanocomposite material, i.e., a porous silicon matrix filled with clusters of exchange-coupled adsorbed molecules. The superparamagnetic behavior of this nanocomposite is detected. It is shown that the saturation magnetic moment remains unchanged in the temperature range from 100 to 360 K and does not degrade in air.