In this paper, results of experimental studies and modeling of standing spin-wave spectra and their temperature evolution in graded Pd-Fe alloy thin magnetic films are presented. Studied sample series include 200-nm thick epitaxial Pd1-xFex films on MgO (001): two with the linear (0.02. .. 0.10 and 0.12... 0.18 x-ranges), one with the sine and one with the cosine (both with 0.02... 0.10 x-range) iron distribution profiles. Versatile spin-wave excitation patterns were obtained, and their pronounced evolution with temperature was observed. Importantly, temperature affects spectra not only in a trivial way via the temperature dependence of magnetization and related quantities, but also through modification of magnetic phase structure of a film due to the Curie temperature crossing by its fraction(s). Continuous at low temperatures magnetization profile becomes discontinuous or significantly altered at elevated ones. Standing spin-wave resonance spectra were modeled using a semiclassical Landau-Lifshitz approach. Based on the modeling, temperature dependences of the spin-wave stiffness D and magnitudes of the interface alpha inter and surface alpha surf pinning constants were obtained. It is shown that, besides a compositional grading of magnetic thin films, the temperature variation is a powerful tool for modifying the magnetization profile and thus, for a flexile tuning of spin-wave spectra.

A review of the recent development in ab initio calculations of the vibrational properties of quasi-one-dimensional (1D) antiferromagnets with AFeX2 structure is presented. Density functional theory (DFT + U) was applied to calculate the phonon modes specific to each element in the structure and the corresponding partial density of states (PDOS). The calculations revealed a strongly non-Debye phonon DOS. Using these results, the nuclear inelastic scattering spectra, temperature dependence of the Lamb-Mössbauer factor, infrared (IR) absorption strength, and phonon-specific heat were derived by direct summation over the phonon modes. The calculations demonstrate good agreement with the experiments and pave the way for understanding the anomalous magnetic properties of AFeX2 quasi-one-dimensional antiferromagnets at a quantitative level.

This work examines the conductivity properties of point contact magnetic tunnel junctions taking into account gradients of the electrochemical potentials at the ferromagnetic metal/dielectric interface. The calculations were carried out for spin -polarized currents at arbitrary ratio the point magnetic tunnel junction size and the mean free paths of conduction electrons under the applied voltage conditions. Current -voltage characteristics were obtained for symmetrical and asymmetrical point junctions.

The static magnetic properties were experimentally studied and magnetization reversal was modeled in an epitaxial thin film of the L10 phase of the PdFe compound and the PdFe/W/PdFe heterostructure on MgO (001) substrates. It was shown that the PdFe/W/PdFe heteroepitaxial structure at an α-W layer thickness of ∼0.7 nm is an artificial antiferromagnet with perpendicular magnetic anisotropy and an exchange integral of J ≃ 1.7 ×10^ - 3 J/m^2 . Micromagnetic modeling of the equilibrium domain structure and its evolution in an external magnetic field made it possible to satisfactorily describe the magnetization reversal curve of the studied thin-film heterostructure.

Anion doping of tungsten trioxide by nitrogen is used to obtain electrochrome cathode materials, the spectral transmittance of which can be controlled by the doping level. A series of samples was synthesized by reactive magnetron sputtering of a metal tungsten target in a mixture of argon, nitrogen, and oxygen gases, the flow rate of the latter was varied at a constant pressure of the gas mixture. Warm-colored tungsten oxynitride films were prepared at higher doping levels with their morphology and elemental composition characterized using scanning electron microscopy, crystal structure described using X-ray diffraction and the valence state of constituents revealed with X-ray photoelectron spectroscopy techniques. Optical properties were measured by making use of transmission spectrophotometry and spectroscopic ellipsometry. These extensive experimental studies revealed an increase in absorption towards shorter wavelengths below the wavelength of 0.5 µm with an increase in the doping level. At the same time, it was found that with an increase in the doping level, partial reduction of the tungsten occurs, and the fraction of non-stoichiometric oxygen steadily increases to half of the total oxygen content. It is a common belief that the imperfection of the doped material facilitates the intercalation of the material by electrolyte ions.

An epitaxial film of a Pd–Fe alloy with a thickness of 202 nm was synthesized with an iron concentration varying in depth from 2 to 10 at

This study demonstrates capabilities of a molecular beam epitaxy method for the deposition of ferromagnetic Pd–Fe alloy thin films with variable compositions across film thickness. It is proposed as a technological route to synthesize graded magnetic materials possessing unusual physical properties. A particular approach to realize a concentration profile through temperature control of an effusion cell during deposition is described in detail. Using this technique, graded ferromagnetic films were synthesized and characterized to reveal the possibility of controlling the spectrum of standing spin waves in them. Limitations of creating Pd–Fe films magnetically profiled across the thickness are discussed, associated with the thermal inertia of effusion cells and possible phase separation.

Results are presented from studying the magnetostatic and magnetoresonant properties of a thin-film bilayer Fe3Al/Pt structure synthesized via molecular beam epitaxy. Magnetometry and ferromagnetic resonance data indicate the four-fold in-plane magnetocrystalline anisotropy of the Fe3Al layer. The magnetic field dependence of the voltage induced by the inverse spin Hall effect is measured under conditions of spin pumping, and the quantitative characteristic of the spin-charge transformation in platinum (the spin Hall angle) is estimated as θSH = 0.030 ± 0.005.

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In the article, a hydrogen exchange between the Zr-1%Nb alloy (E110) and the gas ambient was experimentally studied when the samples were irradiated with deuterium and argon plasma ions. It has been established that, upon irradiation with deuterium plasma ions with an energy of E = 650 eV/at, the enhanced absorption of deuterium exceeds the release of hydrogen initially contained in the samples, which leads to their loading with hydrogen isotopes. Adding 30 at.% oxygen to the plasma-forming gas or raising the sample temperature from T = 450 K to T = 600 K, significantly reduces the content of hydrogen isotopes in the sample. Based on the aggregate data obtained by atomic and ion irradiation, a mechanism of hydrogen exchange between zirconium alloy and gas ambient is proposed. The process includes three stages: reactions on the oxidized surface of the zirconium alloy (surface hydroxylation and formation of water molecules); reactions at the metal-oxide interface; transfer of hydrogen isotopes through the surface oxide layer in both directions due to hopping between neighboring oxygen ions. Surface reactions caused by irradiation of atoms and ions trigger the hydrogen exchange. The proposed model agrees with the experimental data on the irradiation of the E110 alloy with atoms and ions of hydrogen isotopes.

A matrix solution to Usadel linearized equations is used to obtain the critical temperature and distribution of singlet pairing components of a superconductor/ferromagnetic/superconductor/ferromagnetic structure with nonideal boundaries. There is a transition from the π- to the 0-phase state between the superconductor layers upon varying the angle between the magnetizations of ferromagnetic layers in such a structure.

The time-resolved magneto-optical Kerr effect in epitaxial thin films of the FePt compound and the FePt 0.84 Rh 0.16 solid solution with the perpendicular magnetic anisotropy on MgO (001) substrates has been studied. The evolution of hysteresis loops at short (100 fs–1 ns) and long (1–20 ms) time scales after the excitation by a femtosecond light pulse has been studied. Long-lived nonthermal reduction of the coercive field has been detected. The coercive field is recovered in several milliseconds. It has been proposed to explain the observed phenomenon by the excitation of high- Q -factor acoustic resonances in the substrate/film system and to the strong magnetoelastic interaction in FePt and FePt 0.84 Rh 0.16 films.

Magnetic nanoparticles embedded into semiconductors have current perspectives for use in semiconducting spintronics. In this work, 40 keV Fe+ ions were implanted in high fluences of (0.5 ÷ 1.5) × 1017 ion/cm2 into an oxide semiconductor and single-crystalline TiO2 plates of rutile structure with (100) or (001) face orientations. Microstructure, elemental-phase composition, and magnetic properties of the Fe-ion-implanted TiO2 were studied by scanning and transmission electron microscopies (SEM and TEM), X-ray photoelectron (XPS) and Rutherford backscattering (RBS) spectroscopies, as well as vibrating-sample magnetometry (VSM). The high-fluence ion implantation results in the formation of magnetic nanoparticles of metallic iron beneath the irradiated surface of rutile. The induced ferromagnetism and observed two- or four-fold magnetic anisotropy are associated with the endotaxial growth of Fe nanoparticles oriented along the crystallographic axes of TiO2.

The paper presents the results of experiments on the reduction of copper oxides formed during the heat treatment of metallic copper samples in air. The necessary condition is the presence of a muffle made of a material with a higher electron affinity (lower standard electrode potential) compared to copper. Replacing nitrogen in the composition of the atmosphere with an equal proportion of argon does not change the observed redox pattern. Our results indicate an electrochemical mechanism for the reduction of copper oxides in a steel muffle, in which oxygen plays the role of a charge carrier. Keywords: oxidation of metallic copper, reduction of copper oxides, steel muffle, air, oxygen, electrochemistry.

The time-resolved magneto-optical Kerr effect in epitaxial thin films of the FePt compound and the FePt 0.84 Rh 0.16 solid solution with the perpendicular magnetic anisotropy on MgO (001) substrates has been studied. The evolution of hysteresis loops at short (100 fs–1 ns) and long (1–20 ms) time scales after the excitation by a femtosecond light pulse has been studied. Long-lived nonthermal reduction of the coercive field has been detected. The coercive field is recovered in several milliseconds. It has been proposed to explain the observed phenomenon by the excitation of high- Q -factor acoustic resonances in the substrate/film system and to the strong magnetoelastic interaction in FePt and FePt 0.84 Rh 0.16 films.

An epitaxial film of the Pd-Fe alloy 116 nm thick with an iron concentration varying in depth from 2 at.% to 50 at.% has been synthesized. An experimental depth distribution profile of iron was obtained as a result of stepwise etching of the film surface with Ar+ ions. Profiling showed that, as a result of annealing, the impurity was redistributed in the film, and a layer of the L10-phase with a constant concentration was formed near the film surface. After removal of the L10-phase, the film exhibits easy-plane anisotropy. The study of spin-wave resonance spectra showed the presence of several modes of standing spin waves, the number of which depends on the residual film thickness.

An epitaxial film of the Pd-Fe alloy 116 nm thick with an iron concentration varying in depth from 2 at.% to 50 at.% has been synthesized. An experimental depth distribution profile of iron was obtained as a result of stepwise etching of the film surface with Ar + ions. Profiling has shown that, as a result of annealing, the impurity was redistributed in the film, and a layer of the L1 0 -phase with a constant concentration was formed near the film surface. After removal of the L1 0 -phase, the film exhibits "easy-plane" anisotropy. The study of spin-wave resonance spectra showed the presence of several modes of standing spin waves, the number of which depends on the residual film thickness. Keywords: graded magnetic materials, molecular beam epitaxy, palladium-iron alloys, X-ray diffraction, spin-wave resonance.