The epitaxial alignment of Mn2GaC MAX phase on 12 common single‐crystalline substrates is analyzed through a crystallographical approach utilizing near‐coincidence site lattices. This method effectively predicts epitaxial relationships in MAX phase thin films grown on (111) and (001), as well as prospective rutile, muscovite, and substrates, highlighting the chemical affinities and atomic configurations at their interfaces. Novel epitaxial relationships for Mn2GaC MAX phase are identified, offering alternatives to the traditional (001) out‐of‐plane orientation and exploring variations in epitaxial lattice stress. Additionally, this study examines the temperature dependence of interface strain for the most promising orientation relationship candidates, offering insights into the effect of substrate temperature on the growth of the MAX phase thin films.

The effect of the MnxGey buffer layer on the morphology, transport and magnetic properties of Mn5Ge3 thin films grown on substrates Si(111) has been studied. Using X-ray diffraction analysis and atomic force microscopy, it has been found that changing the thickness and structure of the buffer layer with a gradient MnxGey composition has made it possible to control the crystalline quality and smoothness of epitaxial films. Changes in the microstructure and surface roughness has not affected the temperature of the phase transitions revealed from the temperature dependences of the resistivity and magnetization at 75 and 300 K. It has been shown that the features of the magnetization curve shape for films with different buffer layers have been closely related to the inhomogeneity of the films in thickness and surface roughness while maintaining the micromagnetic constants and orientation of the easy magnetization axis. The value of the change in the magnetic part of entropy ΔS has been calculated to be 2.1 J kg–1 K–1 at 1 T, which is comparable with the value for gadolinium and exceeds that for Mn5Ge3(001) films grown on GaAs substrates.

The energy and electronic characteristics, as well as crystal parameters of the (Cr1-xMnx)(2)GeC MAX phase with x = 0.00, 0.25, 0.33, 0.50, 0.67, 0.75, and 1.00 were determined using quantum chemical calculations. As the manganese concentration increases, the stability of the compound is expected to decrease. However, the possibility of experimentally realizing a structure with x > 0.25 has been shown. Epitaxial thin (Cr1-xMnx)(2)GeC MAX films with x up to 0.33 were synthesized by magnetron co-deposition at an increased technological carbon concentration. The samples were studied using electron spectroscopy, high-energy electron diffraction, X-ray diffraction, atomic force microscopy, high-resolution transmission electron microscopy and reflection spectral ellipsometry. The additional graphitic carbon is identified in the films and is attributed to the peculiarities of the deposition method. An increase in x results in an increase in the parameters of the crystal lattice, a deterioration of the crystalline order, and a decrease in optical conductivity. However, a low manganese concentration (x = 0.25) enhances epitaxy compared to Cr2GeC. A threefold increase in the thickness of the (Cr0.75Mn0.25)(2)GeC film results in an increase in the fraction of the secondary (013) structure and a weakening of the primary (00L) structure, though the single-phase nature of the film is preserved.

Magnetic nanoparticles, consisting of a metallic iron core with a shell of gold and iron oxides, were synthesized by ultra-high vacuum surface nucleation on a water-soluble NaCl substrate followed by oxidation in water. Using the methods of electron microscopy, electron diffraction, photoelectron spectroscopy and calculation of the specific density of iron in the oxidized shell, the oxides gamma-Fe2O3, Fe3O4 and oxyhydroxide alpha-FeO(OH) were discovered. A non-uniform distribution of the Fe3+/Fe2+ ion ratio over the particle depth and a predominance of alpha-FeO(OH) in the contrast shell of nanoparticles, directly observed in transmission electron microscopy, were discovered. Comparison of the magnetic properties of partially gold-coated particles with similar Fe particles without gold showed a larger residual volume of unoxidized metal core with partial gold coating. This points to the anisotropy of the surface chemical properties associated with the Janus-like structure. For the first time, the magnetodynamic properties of partially gold-coated Fe nanoparticles were assessed by ellipsometric measurements of the surface of a colloidal solution in a gradient magnetic field.

Light-induced transport phenomena in semiconductor-based structures with magnetic layers, have been the subject of significant scientific research. One notable mechanism for inducing magnetotransport effects in semiconductor-based devices is the lateral photovoltaic effect (LPE), which arises from the separation of photogenerated carriers under illumination. We present a study on the simulation of spectral dependence of diffusion-induced photovoltage in Mn/SiO2/n-Si hybrid structure. By analyzing both lateral and transverse photovoltaic effects in terms of light absorption depth, we gain a deeper insight of the mechanisms governing light-induced transport. The magnetic field's effect on photovoltage is attributed to the Lorentz force and sample's geometry. Additionally, the photovoltage's dependence on the magnetic field exhibits ferromagnetic hysteresis, suggesting the presence of a ferromagnetic MnSi phase near the Mn/SiO2 interface.

High-vacuum carbosilicothermic reduction of MnOx thin films on Si(100) substrates was investigated in the temperature range of 200-700 degrees C using in-situ Auger electron spectroscopy along with mass spectroscopy and ex-situ X-ray photoelectron spectroscopy. Carbothermic reduction of manganese, accompanied by the CO evolution, occurs over the entire temperature range. When heated above 500 degrees C, silicothermic reduction and formation of manganese silicides are observed. The efficiency of carbothermic reduction of Mn in thin films turned out to be higher at C:Mn = 1:10 than at C:Mn = 1:5. Carbon in the samples is assumed to be present in two forms: as amorphous carbon in a mixture with oxygen and manganese, and as individual, larger particles with a graphite structure. The particle size depends on the power of the magnetron source and influences the carbon coalescence activity, which competes with the carbothermic reduction process. The efficiency of silicothermic reduction on the film surface depends on the initial carbon concentration.

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

Auger electron spectroscopy was used to determine the phase composition of Cr 2 GeC MAX phase thin films. A distinctive feature of the formation of carbon-containing MAX phases is the shape of carbon Auger peaks, which is characteristic of metal carbides spectra. Features of the Auger spectra in the presence of secondary phases of chromium germanides are found. Their presence can manifest itself in an increase in the energy of the germanium peaks, which is caused by a chemical shift during the formation of the Cr–Ge bond. Moreover, we have detected the accumulation of electronic charge, which can be explained by the features of the surface morphology.

Charge transport in semiconductor devices is highly sensitive to light, which opens up wide application pros-pects. The lateral photovoltaic effect (LPE) is widely used in position sensitive detectors due to its high sensitivity to the light spot position. We report on the features of the LPE in silicon-based metal/insulator/semiconductor structures at helium temperatures. To investigate the LPE, Fe/SiO2/p-Si and Mn/SiO2/n-Si structures have been fabricated by molecular beam epitaxy. It has been found by studying the lateral photovoltage that the SiO2/Si interface plays a significant role in transport of photogenerated carriers, mainly via the interface states, which induce electron capture/emission processes at certain temperatures. The value of the photovoltage is likely affected not only by the metallic film thickness, but also by the substrate conductivity type and Schottky barrier. The effect of the magnetic field on the LPE is driven by two mechanisms. The first one is the well-known action of the Lorentz force on photogenerated carriers and the second one is shifting of the interface state energy levels. Basically, the magnetic field suppresses the contribution of the interface states to the LPE, which suggests that the interface-induced transport can be controlled magnetically.

We have analyzed chemical bonding of atmospheric oxygen with chromium and manganese on the epitaxial MAX-phase (Cr0.5Mn0.5)2GaC surface using Auger electron spectroscopy combined with ion etching. It was found that the system has a specific anisotropic oxidation where oxygen atoms bind to chromium and manganese ones more actively at the edges of layered MAX phase crystallites in contrast to the (0001) basal plane. At the same time, the dominance of the Mn-O chemical bonding over Cr-O is observed on the latter.

Using Density Functional Theory and Periodic Boundary Conditions it is shown that the hydroxylated/oxygenated/halogenated Mn2C monolayer is a 2D ferromagnetic material with a local Mn ions magnetic moment of 2.7μв per unit cell. Upon oxygenation the ferromagnetic coupling between Mn ions can be transformed into a superposition of magnetic states. In particular, the intrinsic magnetic moments in the hydroxylated/halogenated Mn2C monolayer can attain up to 6μB per unit cell. It is found that oxygen termination induces flat bands in the band structure, which evidence for the strong electron correlations and could lead to the implementation of exotic quantum phases in 2D crystals and high-temperature superconductivity. Along with the potential of the hydroxylated Mn2C monolayer characterized by the half-metallicity for application in spintronic devices as a perfect spin injector/detector, this material like other conventional MXenes is promising for the use in energy storage, electromagnetic interference shielding, and sensing.

In this paper, we solve the inverse problem of magneto-optical ellipsometry for thin ferromagnetic films with optical uniaxial anisotropy. We work within the framework of the approach we developed earlier analyzing magnetoellipsometric data without using fourth-order M-matrices. We work with ellipsometric relations, in which we take into account the magneto-optical contribution as perturbations, and ellipsometric measurements are carried out on a setup with a simple dipole scheme based on the transverse magneto-optical Kerr effect. We add the magneto-optical response to the expressions known in the literature for the reflection coefficients of anisotropic thin films, which are related to the parameters measured by magneto-optical ellipsometry. As a result, by analyzing the obtained expressions for the reflection coefficients, we obtain information on the total permittivity tensor of a thin film.

The use of spintronic devices with a tunable magnetic order on small scales is highly important for novel applications. The MAX phases containing transition metals and/or magnetic ion-substituted lattices attract a lot of attention. In this study, the magnetic and electronic properties of (Cr4-xFex)0.5AC (A = Ge, Si, Al) compounds were predicted and investigated within the density functional theory. It was established that single-substituted (Cr3Fe1)0.5AC (A = Ge, Si, Al) lattices are favorable in terms of energy. An analysis of the magnetic states of the MAX phases demonstrated that their spin order changes upon substitution of iron atoms for chromium ones. It was found that mostly the (Cr4-xFex)0.5GeC and (Cr4-xFex)0.5AlC lattices acquire a ferrimagnetic state in contrast to (Cr4-xFex)0.5SiC for which the ferromagnetic spin order dominates. It was pointed out that the atomic substitution could be an efficient way to tune the magnetic properties of proposed (Cr4-xFex)0.5AC (A = Ge, Si, Al) MAX phases.

The growth and phase formation features, along with the influence of structure and morphology on the electronic, optical, and transport properties of Cr2GeC and Cr2-xMnxGeC MAX phase thin films synthesized by magnetron sputtering technique, were studied. It was found that the Cr:Ge:C atomic ratios most likely play the main role in the formation of a thin film of the MAX phase. A slight excess of carbon and manganese doping significantly improved the phase composition of the films. Cr2GeC films with a thicknesses exceeding 40 nm consisted of crystallites with well-developed facets, exhibiting metallic optical and transport properties. The hopping conduction observed in the Cr2-xMnxGeC film could be attributed to the columnar form of crystallites. Calculations based on a two-band model indicated high carrier concentrations N, P and mobility μ in the best-synthesized Cr2GeC film, suggesting transport properties close to single crystal material. The findings of this study can be utilized to enhance the growth technology of MAX phase thin films.

Planar and vertical hybrid structures, which combine ferromagnetic and semiconductor layers are essential for implementation and study of spin transport phenomena in semiconductors, which is crucial for the advancement and development of spintronics. We have developed approaches for the synthesis of Fe 3 + x Si 1 – x epitaxial thin films and demonstrated the spin accumulation effect in multiterminal devices based on Fe 3 + x Si 1 – x /Si. Fe 3 + x Si 1 – x /Ge/Fe 3 Si and Fe 3 + x Si 1 – x /Ge/Mn 5 Ge 3 multilayer hybrid structures were synthesized on a Si(111) substrate, study of their structural, magnetic and transport properties were performed. The effect of synthesis conditions on the growth of epitaxial structures and on their magnetic and transport properties was discussed. The results obtained may prove valuable in the development and fabrication of spintronic devices.

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

Three-layer iron-rich Fe3+xSi1−x/Ge/Fe3+xSi1−x (0.2 < x < 0.64) heterostructures on a Si(111) surface with Ge thicknesses of 4 nm and 7 nm were grown by molecular beam epitaxy. Systematic studies of the structural and morphological properties of the synthesized samples have shown that an increase in the Ge thickness causes a prolonged atomic diffusion through the interfaces, which significantly increases the lattice misfits in the Ge/Fe3+xSi1−x heterosystem due to the incorporation of Ge atoms into the Fe3+xSi1−x bottom layer. The resultant lowering of the total free energy caused by the development of the surface roughness results in a transition from an epitaxial to a polycrystalline growth of the upper Fe3+xSi1−x. The average lattice distortion and residual stress of the upper Fe3+xSi1−x were determined by electron diffraction and theoretical calculations to be equivalent to 0.2 GPa for the upper epitaxial layer with a volume misfit of −0.63% compared with a undistorted counterpart. The volume misfit follows the resultant interatomic misfit of |0.42|% with the bottom Ge layer, independently determined by atomic force microscopy. The variation in structural order and morphology significantly changes the magnetic properties of the upper Fe3+xSi1−x layer and leads to a subtle effect on the transport properties of the Ge layer. Both hysteresis loops and FMR spectra differ for the structures with 4 nm and 7 nm Ge layers. The FMR spectra exhibit two distinct absorption lines corresponding to two layers of ferromagnetic Fe3+xSi1−x films. At the same time, a third FMR line appears in the sample with the thicker Ge. The angular dependences of the resonance field of the FMR spectra measured in the plane of the film have a pronounced easy-axis type anisotropy, as well as an anisotropy corresponding to the cubic crystal symmetry of Fe3+xSi1−x, which implies the epitaxial orientation relationship of Fe3+xSi1−x (111)[0−11] || Ge(111)[1−10] || Fe3+xSi1−x (111)[0−11] || Si(111)[1−10]. Calculated from ferromagnetic resonance (FMR) data saturation magnetization exceeds 1000 kA/m. The temperature dependence of the electrical resistivity of a Ge layer with thicknesses of 4 nm and 7 nm is of semiconducting type, which is, however, determined by different transport mechanisms.

Mn5Ge3 epitaxial thin films previously grown mainly on Ge substrate have been synthesized on Si(111) using the co-deposition of Mn and Ge at a temperature of 390 °C. RMS roughness decreases by almost a factor of two in the transition from a completely polycrystalline to a highly ordered growth mode. This mode has been stabilized by changing the ratio of the Mn and Ge evaporation rate from the stoichiometric in the buffer layer. Highly ordered Mn5Ge3 film has two azimuthal crystallite orientations, namely Mn5Ge3 (001) [1-10] and Mn5Ge3 (001) [010] matching Si(111)[-110]. Lattice parameters derived a (7.112(1) Å) and c (5.027(1) Å) are close to the bulk values. Considering all structural data, we proposed a double buffer layer model suggesting that all layers have identical crystal structure with P6₃/mcm symmetry similar to Mn5Ge3, but orientation and level of Si concentration are different, which eliminates 8% lattice mismatch between Si and Mn5Ge3 film. Mn5Ge3 film on Si(111) demonstrates no difference in magnetic properties compared to other reported films. TC is about 300 K, which implies no significant excess of Mn or Si doping. It means that the buffer layer not only serves as a platform for the growth of the relaxed Mn5Ge3 film, but is also a good diffusion barrier.

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