X-ray and magnetometry methods are used to show that, during magnetron sputtering of Dy/Co periodic multilayer systems, the DyCo2 and DyCo3 intermetallics form. The main reason for the phase formation of various intermetallics is the structural state of buffer layer, namely, its crystalline and amorphous state in the case of crystalline and glass substrate, respectively.

The microwave magnetoresistance of CoFe/Cu/CoFe/FeMn spin valves and CoFe/Cu/CoFe three-layer nanostructures with high magnetoresistance has been studied. The transmission and reflection coefficients were measured at the frequency range from 26 to 38 GHz in magnetic fields up to 12 kOe. It is shown that the dependences of the transmission coefficient of spin valves are not symmetric with respect to the H=0 axis, as well as the dependences of magnetoresistance. It is established that the relative changes in the microwave transmission coefficient are 1.5-2 times higher than the relative magnetoresistance measured at direct current. Changes in the reflection coefficient have a smaller value and the opposite sign with respect to changes in the transmission coefficient. Keywords: metal superlattices, spin valves, ferromagnetic resonance, ferromagnetic antiresonance, microwave giant magnetoresistance effect.

Spin valves with a CoFe/Dy/CoFe composition in the lower part of their structure have been manufactured by magnetron sputtering. The effect of prolonged storage and temperature on the structure and magnetotransport properties of spin valves has been studied. The change in the compensation temperature was used as an indicator of the intensity of diffusion processes in the exchange-coupled CoFe/Dy/CoFe structure. It has been revealed that diffusion induced changes in the magnetotransport properties become smaller with a decrease in the dysprosium layer thickness. It has been shown that the nanostructure still contains pure dysprosium, the atoms of which do not participate in the sperimagnetic ordering of the Dy–Co–Fe interface, even at a small nominal thickness (4 nm) of the dysprosium layer 3 months after sputtering.

X-ray reflectometry (XRR) and X-ray photoelectron spectroscopy (XPS) measurements (core levels and valence bands) were made of Cu thin films that were prepared and coated by capping Ta layers with different thicknesses (5, 10, 15, 20, and 30 Å), and are presented. The XRR and XPS Ta 4f-spectra revealed a complete oxidation of the protective layer up to a thickness of 10 Å. From the thickness of the capping layer of 15 Å, a pure Ta-metal line appeared in the XPS Ta 4f-spectrum, the contribution of which increased up to 30 Å. The XPS Cu 2p-spectra of the underlying copper layer revealed the oxidation with the formation of CuO up to a thickness of the Ta-layer of 10 Å. Starting from a thickness of 15 Å, the complete protection of the Cu layer against oxidation was ensured during exposure to the ambient atmosphere.

Optical and magneto-optical properties of the La0.65Ba0.35MnO3 /SrTiO3(0 0 1) thin film with CMR and the paramagnetic-to-ferromagnetic transition at T = 310 K have been investigated in the infrared spectral range. It is shown that magnetotransmission and magnetoreflection of unpolarized light in the film reach up to 10 % at the magnetic field of 4 kOe. The possible physical mechanisms responsible for negative magnetotransmission and positive magnetoreflection in the mid-infrared range are interpreted in the framework of the theory of magne-torefractive effect in manganites. High optical response of the La0.65Ba0.35MnO3 film to an external magnetic field (up to -25 %/kOe in the magnetoreflection) could be used in the design of optical magnetic field sensor, switches and modulators.

It is shown that CuIn alloys can be effectively used as spacers in GMR multilayers. Attention is paid to the method of obtaining of the homogeneous CuIn alloys. Magnetron targets Cu1-xInx with an indium content = 2-8.7 at% have been used for preparation of exchange-coupled multilayers of the composition glass/Ta (5)/Ni48Fe12Cr40(5)/[Co90Fe10(1.3)/Cu1-xInx(2-2.2 nm)]7/Ta(5). A decrease in GMR ratio was found with an increase in the content of indium in the alloy Cu1-xInx. For x < 4.7 at% a slight decrease in magnetoresistance is observed. The sharpest decrease in the GMR ratio from 23.3% to 3.2% is observed when the indium content changes in the range x = 4.7-8.7 at%. It is demonstrated that the coercivity of CoFe/Cu1-xInx multilayers decreases more than 5 times when the indium content increases in the range of = 0-4.7 at. %. A correlation between the crystallite sizes in multilayers and the change of coercivity has been revealed. It is shown that the substitution in the multilayers studied of Co90Fe10 alloy by Co-rich ternary ferromagnetic alloys Co77Fe17Ni6 and Co70Fe20Ni10 made it possible to obtain CoFeNi/CuIn multilayers with GMR ratio of 25-29%, extremely low coercivity of several Oe, and high linearity of the field dependence of magnetoresistance. The combination of these characteristics is useful for practical applications. (c) 2022 Elsevier B.V. All rights reserved.

The structure, magnetic and electrical properties of low-carbon 2% Mn-doped steel manufactured by selective laser melting (3D-steel) and casting have been investigated. It was found that after normalization at 980oC for 30 minutes, 3D-steel becomes structurally similar to cast steel, while the hardness decreases by 70% compared to annealed 3D-steel. Surface stresses are maximum in as-build 3D-steel after three-hour annealing. The normalization process significantly reduced the level of residual stresses, which was confirmed via the X-ray structural analysis and magnetometric measurements. The coercive force and r remanence of normalized 3D-steel are comparable with similar properties of normalized cast steel, which indicates similar structural and stress-strain states of cast and 3D-steels. Keywords: selective laser melting, low-carbon steel doped with 2% manganese, structure, residual stresses, magnetic properties.

The microwave magnetoresistance of CoFe/Cu/CoFe/FeMn spin valves and CoFe/Cu/CoFe three-layer nanostructures with high magnetoresistance has been studied. The transmission and reflection coefficients were measured at the frequency range from 26 to 38 GHz in magnetic fields up to 12 kOe. It is shown that the dependences of the transmission coefficient of spin valves are not symmetric with respect to the H=0 axis, as well as the dependences of magnetoresistance. It is established that the relative changes in the microwave transmission coefficient are 1.5-2 times higher than the relative magnetoresistance measured at direct current. Changes in the reflection coefficient have a smaller value and the opposite sign with respect to changes in the transmission coefficient. Keywords: metal superlattices, spin valves, ferromagnetic resonance, ferromagnetic antiresonance, microwave giant magnetoresistance effect.

The texture of deformation and primary recrystallization in copper-nickel alloys with the addition of a small amount of refractory elements such as Nb, Mo, Ta and W was studied. Based on the X-ray analysis of the deformation texture using the orientation distribution function, it was shown that the volume fraction of the C and S components in alloys is greater than the double volume fraction of the unfavorable component B. In accordance with this criterion, after primary recrystallization in all the studied alloys, a sharp cubic texture {100}< 001 > was obtained with a volume fraction in the± 10° region of more than 95%. Alloying with refractory elements significantly increases the strength of the base copper-nickel alloy by the mechanism of solid-solution hardening. The evaluation of the mechanical characteristics showed that the increase in the yield stress in the studied alloys is from 25% to 45% with relative to Cu-40% Ni alloy.

The microwave magnetoresistance of CoFe/Cu/CoFe/FeMn spin valves and CoFe/Cu/CoFe three-layer nanostructures with high magnetoresistance has been studied. The transmission and reflection coefficients were measured at the frequency range from 26 to 38 GHz in magnetic fields up to 12 kOe. It is shown that the dependences of the transmission coefficient of spin valves are not symmetric with respect to the H = 0 axis, as well as the dependences of magnetoresistance. It is established that the relative changes in the microwave transmission coefficient are 1.5–2 times higher than the relative magnetoresistance measured at direct current. Changes in the reflection coefficient have a smaller value and the opposite sign with respect to changes in the transmission coefficient.

The structure, magnetic, and electrical properties of the 09G2S steel prepared by selective laser melting (3D steel) and casting are studied. It is found that the 3D 09G2S steel becomes similar in structure to the cast steel after normalization at 980°C for 30 min; in this case, the hardness decreases by 70% as compared to the annealed 3D steel. The surface stresses are maximal in the 3D steel after its preparation and 3-hour annealing. The normalization enables us to substantially decrease the residual stresses, which is confirmed by the X-ray diffraction and magnetometric measurements. The coercive force and the remanence of the normalized 09G2S steel are comparable with similar properties of the normalized cast 09G2S steel, which demonstrates the similarity of the structural and stress–strain states of the cast and 3D steels.

N. O. Antropov, 2 E. A. Kravtsov, M. V. Makarova, V. V. Proglyado, T. Keller, 4 I. A. Subbotin, E. M. Pashaev, G. V. Prutskov, A. L. Vasiliev, Yu. M. Chesnokov, N. G. Bebenin, V. V. Ustinov, B. Keimer, and Yu. N. Khaydukov 4, 6 Institute of Metal Physics, 620180 Ekaterinburg, Russia Ural Federal University, 620002 Ekaterinburg, Russia Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany Max Planck Society Outstation at the Heinz Maier-Leibnitz Zentrum (MLZ), D-85748 Garching, Germany National Research Center ”Kurchatov Institute”, 123182 Moscow, Russia Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow 119991, Russia (Dated: February 2, 2021)

Исследованы структура, магнитные и электрические свойства конструкционной сталей 09Г2С, полученных методом селективного лазерного сплавления (3d- сталь) и литьем. Установлено, что после нормализации при 980 o С в течение 30 минут 3d-сталь 09Г2С становится структурно похожа на литую сталь, при этом твердость уменьшается на 70% по сравнению с отожженной 3d-сталью. Поверхностные напряжения максимальны в 3d-стали после изготовления и трехчасового отжига. Нормализация позволяет существенно снизить уровень остаточных напряжений, что подтверждают результаты рентгеноструктурного анализа и магнитометрических измерений. Коэрцитивная сила и остаточная магнитная индукция нормализованной 3d-стали 09Г2С сопоставимы с аналогичными свойствами литой нормализованной стали 09Г2С, что свидетельствует о схожем структурном и напряженно-деформированном состояниях литой и 3d-сталей. Ключевые слова:селективное лазерное сплавление, сталь 09Г2С, структура, остаточные напряжения, магнитные свойства.

Dysprosium-based bottom spin valves with the thickness of the dysprosium layer comparable to the spatial period of the magnetic helicoid were fabricated by magnetron sputtering. Perfect fiber crystal texture was obtained in Dy layer sputtered on Ta underlayer. The inversion of magnetoresistive curves with temperature decreasing is observed. The explanation of these features is based on the paramagnet-antiferromagnet transition in dysprosium nanolayer and on the deformation of helicoidal magnetic structure by an applied magnetic field. It has been determined that at the same temperature and field the smaller is the thickness of the ultra-thin dysprosium layer, the greater is its magnetic moment. The Neel temperature was estimated for dysprosium nanolayer in Ta/Dy/Ta structures where the smallest thickness of the dysprosium layer was 10 nm. It has been revealed that the temperature of transition from paramagnetic to antiferromagnetic state is different in the film regions in which helicoid axis is close to parallel or perpendicular to the film plane.

The dependence of the Neel temperature on the thickness of the dysprosium layer has been studied. It is shown that the temperature range within which the paramagnetic–antiferromagnetic phase transition takes place depends on the microstructure and thickness of the dysprosium layer. Spin valves based on a CoFe alloy with dysprosium as an antiferromagnetic layer are manufactured via magnetron sputtering. It is shown that unidirectional anisotropy forms in the CoFe/Dy interface. The direction of the exchange bias field depends on the direction of the magnetic moment of the CoFe layer in the formation of exchange coupling.

The influence of structural properties on the formation of perpendicular magnetic anisotropy in Co/Dy superlattices is investigated. It is established that superlattices are a compositionally modulated alloy in which, on the one hand, a strict periodicity is maintained in the thickness and composition of the layers, and on the other hand, the interdiffusion of Co and Dy at the interlayer boundaries leads to a periodic change with the depth of the concentration of Co and Dy. It is shown that the perpendicular magnetic anisotropy in Co/Dy is due to the perpendicular orientation of the magnetization in the alloying CoDy layers, while the magnetization of the Co layers is oriented in the sample plane.

Spin valves with holmium layers and three-layer structures metal/Ho/metal were prepared by magnetron sputtering. A holmium layer in the spin valves is polycrystalline with weak axial <002> texture. The structural coherence length along the hexagonal c-axis is approximately 2/5 of the total thickness of the holmium layer. Field dependences of the spin valves magnetoresistance were measured at different temperatures. Correlation was revealed between magnetic state in holmium layer and the shape of magnetoresistive curve. Deviation of magnetic moments of the reference layer and the adjacent part of holmium from the applied magnetic field was investigated. The field induced mobility of the magnetic helicoid in holmium layers was revealed.