bluuebunny/crossref_metadata_2025 huggingface dataset:
Untwisting of a soft ferrocholesteric liquid crystal by shear flow and magnetic field
Authors: Novikov Alexander , Makarov Dmitriy
Published: November 2019

We theoretically study the effect of a shear flow and a uniform magnetic field on the helical structure of a ferrocholesteric liquid crystal with the finite anchoring between the liquid-crystalline matrix and magnetic particles (soft ferrocholesteric). The axis of the ferrocholesteric helix is orthogonal to the plane of the shear flow and the magnetic field. We derive the integral expressions for the pitch of the helix and magnetization of ferrocholesteric depending on the anchoring energy, field influence parameter, strength and orientation angle of the magnetic field, flow gradient and reactive parameter. It is shown that the shear flow is able to magnetize a ferrocholesteric liquid crystal. An increase in the field influence parameter or gradient of the shear flow velocity leads to a decrease in the critical fields of the ferrocholesteric-ferronematic transition.
Investigation of magnetic emulsions in magnetic field by rotating test-tube method
Authors: Belykh S , Yerin C
Published: November 2019

The effect of diffraction scattering of light in a magnetic emulsion in a magnetic field in a rotating test-tube has been investigated. The non-linear dependence of the angle of deviation of the diffraction band on the rotation speed is established. An interpretation of the effect is proposed based on the balance of torques from the magnetic field and the drag force of the fluid. Agreement with the experiment is possible on the assumption of the destruction of the chains of magnetic emulsion microdroplets during rotation.
Influence of uniform magnetic field on elastic modulus in polyacrylamide ferrogels with embedded nickel nanoparticles
Authors: Mikhnevich E A , Chebotkova P D , Safronov A P , Kurlyandskaya G V
Published: November 2019

Polyacrylamide ferrogels with embedded nickel magnetic nanoparticles were synthesized by radical polymerization in water. The elastic modulus of ferrogels was measured under unidirectional compression in a uniform magnetic field with a strength of 0, 165, 220 and 275 Oe. With an increase in the content of nickel particles in ferrogel from 0 to 5.3% by weight, the elastic modulus in zero magnetic field increased by 60%. The application of magnetic field parallel to the direction of compression resulted in the increase of modulus, and if the field was applied perpendicular to the compression, the modulus tends to decrease. Such trends are in good agreement with the features of magnetostriction of a non-compressible uniformly magnetized sphere in a constant magnetic field.
Neutron reflectometry studies of Gd/Nb and Cu30Ni70/Nb superlattices
Authors: Khaydukov Y , Kravtsov E , Morari R , Lenk D , Mustafa L , Kim G , Trapp M , Zhaketov V , Proglyado V , Zrdavkov V , Nikitenko Y , Krug von Nidda H-A , Keller T , Steitz R , Tideks R , Sidorenko A , Ustinov V , Aksenov V , Keimer B
Published: November 2019

We performed a comparative study of magnetic proximity effects in [Gd(5nm)/Nb(25nm)]12 and [Cu30Ni70(6nm)/Nb(27nm)]12 superlattices of S/F type by means of transport measurements and neutron scattering. Transport measurements have shown that Gd/Nb and CuNi/Nb superlattices shows 3D and 2D type of superconductivity respectively. In the case of proximity coupled Gd/Nb superconductor the effective thickness of the superconducting region, 300nm is enough to expel significant amount of applied magnetic field which was detected by neutron scattering. In decoupled CuNi/Nb superlattice thickness of every superconducting layer is only 27nm which is not enough to expel applied magnetic field. Our study shows how neutron reflectometry can be applied to study proximity coupling in superconducting/ferromagnet heterostructures.
Magnetic properties of Chelyabinsk meteorite (15 February 2013) at high temperatures
Authors: Korolev A V , Kurmaev E Z
Published: November 2019

Magnetic properties of the Chelyabinsk meteorite were studied in a wide temperature range – up to ~ 1300 K. The analysis shows that the meteorite contains ferromagnetic inclusions of both Fe-Ni alloy and pure iron. It has visually been demonstrated that iron inclusions of the Chelyabinsk meteorite experience no β→γ structural phase transformation.
Formation and structure of Nb3Sn layers in bronze-processed superconductors under various intermediate heat treatments
Authors: Popova E N , Deryagina I L
Published: November 2019

Multifilamentary Nb3Sn-based superconducting wires are created and used for various superconducting magnetic systems such as thermonuclear reactors and future large accelerator projects. The crucial role in achieving high superconducting characteristics is played by the structure of Nb3Sn layers, which, in its turn, is determined by a number of factors, such as fabrication route, composition, annealing schedules, etc. In the present study the superconducting layers formation and structure have been studied by SEM and TEM after various regimes of intermediate heat treatments and two-staged diffusion annealing. Optimal heat treatment schedules for the formation of perfect nanocrystalline structure of Nb3Sn layers for an achievement of highest critical current densities have been revealed.
Microstructure and critical current of bulk MgB2 superconductor
Authors: Krinitsina T P , Kuznetsova E I , Blinova Y V , Degtyarev M V
Published: November 2019

The structure of bulk MgB2 specimens after cold deformation in Bridgeman anvils and “Toroid” chamber and following recovery annealings has been studied by scanning and transmission electron microscopy. It is demonstrated that in spite of the matrix phase grain coarsening by 5-7 times under annealing compared to the as-deformed state, the critical current density increases by a factor of 3 (6.7×104 A/cm2 at 30 K after deformation in the “Toroid” chamber and recovery annealing).
Application of NMR for quantification of magnetic nanoparticles and development of paper-based assay
Authors: Minin A S , Uymin M A , Yermakov A Ye , Byzov I V , Mysik A A , Rayev M B , Khramtsov P V , Zhakov S V , Volegov A V , Zubarev I V
Published: November 2019

H1 NMR relaxometry is a method that is extremely sensitive to the presence of magnetic nanoparticles, which significantly affect the transverse relaxation time of the water proton. Accordingly, the use of magnetic nanoparticles as labels allows detection of even extremely small amounts of the test substance. This paper analyzes the prospects for applying the method of solid-phase NMR-relaxometric determination of biologically active molecules. The nitrocellulose membranes are chosen as a solid phase and nanoparticles based on iron core with a carbon shell are used as magnetic labels. The possibility of detecting small concentrations of magnetic particles in porous medium is demonstrated. Finally, the ability to detect extremely low concentrations of an analyte, in this case, streptavidin protein (0.5 ng/ml to 100 ng/ml), which is actively used in various fields of biology and medicine, is demonstrated.
Two types of magnetite-containing liposomes for magnetocontrolled drug release
Authors: Zharkov M N , Gerasimov M V , Trushina D B , Khmelenin D N , Gromova E V , Yakobson D E , Pyataev M A
Published: November 2019

The paper is dedicated to a comparative study of pharmaceutical properties of magnetite containing liposomes. We have investigated two types of liposomes: 1) magnetic shell liposomes containing magnetic nanoparticles in the coating lipid bilayer and 2) magnetic core liposomes containing the nanoparticles in the internal volume (water phase). Both types of liposomes were obtained by the thin film hydration method from phosphatidylcholine and cholesterol. Fluorescent dye 5,6-carboxyfluorescein was used as a marker substance to indicate release. The dimensional characteristics, the degree of dye release under the influence of an alternating magnetic field, the speed of spontaneous release and the stability of liposomes during storage were investigated. It has been shown that liposomes with nanoparticles in the internal space are more stable, have low rate of spontaneous release of the incorporated substance, but the rate of release under the influence of an alternating field is also low. Liposomes with magnetic nanoparticles inside the lipid bilayer have high release degree influenced by alternating magnetic field, but they are less stable during storage and more prone to spontaneous loss of the active substance.
Influense of various forms of iron on growth of Chlorella vulgaris Beijer culture
Authors: Polynov V A , Maksimova E N , Safronov A P , Kurlyandskaya G V
Published: November 2019

A comparative study of the toxic effect of magnetic nanoparticles of iron oxide (MNPs) and ions of bivalent and trivalent iron in the composition of sulfates on the growth of an intensive culture of Chlorella vulgaris Beijer is provided. The high sensitivity of the introduced biotest is shown for the case of a standard toxicant (potassium dichromate). Using the probit-analysis, and semi-extincting specific growth rate of EC50 culture concentrations were established in four-day experiments, which amounted to 1.3 ± 0.2 mg/l for potassium dichromate, 0.8 ± 0.1 mg/l for ferrous iron, 2.0 ± 0.2 mg/l for trivalent 1 and for MNPs iron oxide – 13 ± 1 mg / l. The probit analysis features and the significantly lower semi-suppressing specific growth rate of the culture in experiments with MNPs compared with ionic iron suggests a possible manifestation of other forms of exposure that are not related to the mechanism of chemical intoxication.
Influence of metal containing nanocomposites on the kinetics of microbial population development
Authors: Simonova E V , Kokorina L A , Denisova T P , Maximova E N , Safronov A P , Sorokina A I , Kurlyandskaya G V
Published: November 2019

Magnetic nanoparticles are promising nanomaterials for biomedical applications. Studies have been conducted to study the effect of iron-containing nanoparticles at concentrations of 1.0 and 10.0 maximum tolerated dose for total iron on the growth and development of the microbial population of E.coli. On the basis of the obtained results, it was found that nanoparticles affect the growth characteristics of E.coli, related to human gram-negative prokaryotic microflora. The level of biological activity of nanoparticles depends on their concentration.
Donor DBH excitons and magnetism of Mn doped ZnO
Authors: Sokolov V I , Gruzdev N B , Vazhenin V A , Fokin A V , Korolev A V , Menshenin V V , Surikov V T , Yemelchenko G A
Published: November 2019

In this paper the results of the study of optical absorption, photo-EPR signals and magnetic measurements of hydrothermal single crystals of zinc oxide doped with manganese were presented. Several lines were detected in optical absorption spectra at the temperature of 4.2 K and 77.3 K for σ- and π- polarizations of light in a 1.72–2.3 eV spectral range. These lines are attributed to a donor exciton [(d5 + h)e] that emerges as a result of the Coulomb binding of a free s electron and a hole, which is localized on p–d hybridized states. Properties of these lines are significantly different from the properties of lines of donor and acceptor excitons in II-VI:3d compounds. In EPR-spectra of Zn1-x
Mn
x
O crystals the intensity of allowed and forbidden EPR-signals of Mn2+ (d
5)-ions does not change under the illumination while the intensity of EPR-signals of unintentional Fe3+ (d
5)-ions decreases by 70 %. The value of the magnetic susceptibility of Zn1-x
Mn
x
O (x = 0.0009) is in linear dependence with temperature, which agrees with the Curie equation. Temperature dependence of the inverse value of the Mn2+ magnetic susceptibility indicates that the exchange interaction in ZnO:Mn crystals is absent. New experimental results allow us to assume that investigated Zn1-x
Mn
x
O (x = 0.0009) samples are semiconductors in the forbidden gap of which the donor level of d5/d4 does not exist. The hybridization of d5 states of Mn2+ and p states of the nearest four oxygen ions O2- leads to pushing out the antibonding DBH-states (d
5 + p) into the forbidden gap. The transitions of electrons from DBH-states to the conduction band provide a broad band of the impurity absorption in ZnO:Mn. Below this band we observed a, b, c and d lines, which are called dbh-donor excitons [(d5+h)e].
Spin current and magnetic measurements in heterostructure SrIrO3/La0.7Sr0.3MnO3
Authors: Shaikhulov T A , Demidov V V , Stankevich K L , Ovsyannikov G A
Published: November 2019

The dc voltage on the film SrIrO3 (SIO) generated under ferromagnetic resonance condition has been studied in the heterostructure based on manganite thin epitaxial films La0.7Sr0.3MnO3 (LSMO). The SIO film is a paramagnetic metal with strong spin-orbit interaction in the temperature range 20-300K. The effect is shown to be caused by two different phenomena: (1) the resonance dc electromotive force related to anisotropic magnetoresistance (AMR) in the manganite film and (2) pure spin current (spin pumping) registered by means of the inverse spin Hall effect in upper layer. We also give the results of the magnetic parameters measuring for the heterostructure SIO/LSMO using ferromagnetic resonance in a wide temperature range.
Generalized Quantum Monte Carlo Algorithm in Eigen Basis
Authors: Kashurnikov Vladimir , Krasavin Andrey , Zhumagulov Yaroslav , Kartsev Petr
Published: November 2019

New generalized continuous-time quantum Monte Carlo algorithm is developed. The algorithm is absolutely universal in the sense that it allows to calculate models specified in an arbitrary basis (in the basis of occupation numbers; in the momentum representation; in the basis of the eigenfunctions of small clusters into which the entire system is divided, or in any other basis): the algorithm requires only the specification of the matrix elements between the basis functions defined in a convenient basis. The implemented algorithm is applied to one-dimensional Hubbard model.
Metal–insulator transition in the antiferromagnetic state of the Hubbard model: analytical theory
Authors: Igoshev P A , Irkhin V Yu
Published: November 2019

In the framework of numerical calculations and analytical expansion in the transfer integral between the next-nearest neighbors t’ and the direct antiferromagnetic (AFM) gap ∆, the metal–insulator transition criterion is obtained, the Hartree-Fock and slave boson approaches being used. In the case of a square lattice, there is an interval of t’ values, for which the metal-insulator transition is a first-order transition, which is due to the Van Hove singularity near the center of the band. For simple and body-centered cubic lattices, the transition from the insulator AFM state occurs to the phase of an AFM metal and is a second-order phase transition; it is followed by a transition to a paramagnetic metal. These results are modified when taking into account the intersite Heisenberg interaction which can induce first-order transitions.
Spin fluctuations of the uranium 5f-electrons in UN according to 14N-NMR data
Authors: Ogloblichev Vasily V , Verkhovskii Stanislav V , Potapov Aleksey M , Germov Aleksandr Yu , Sadykov Almaz F
Published: November 2019

The results of the study of the paramagnetic region of uranium mononitride by the method of nuclear magnetic resonance (NMR)of 14N nuclei are presented.The 14N NMR spectra, the Knight shifts K, the spin-lattice relaxation times T
1 have been obtained within the temperature range T = 60 – 375 K and at magnetic fields 92.8 kOe and 117.5 kOe. The temperature dependence of the Knight shift of the 14N line is proportional to the spin susceptibility χ of 5f-electrons of uranium. The ratio of the experimentally determined value T
T
1
K
2 to the theoretically calculated value of the Korringa contribution is 21.5 (at T = 295 K), which is significantly more than for common metals. This suggests that nuclear relaxation is based on the same mechanism as the Knight shift, namely, the indirect connection between the 14N nuclei and the localized magnetic moments of uranium through conduction electrons. The experimental results on the T-dependence of the spin-lattice relaxation rate of 14N also do not contradict the assumption that uranium mononitride is a concentrated Kondo system.
Temperature hysteresis in bilayer FeRh/PZT structure
Authors: Starkov Ivan , Amirov Abdulkarim , Nikulin Viacheslav , Starkov Konstantin , Starkov Alexander
Published: November 2019

We investigate temperature hysteresis of magnetization in a two-layer composite structure composed of magnetocaloric and electrocaloric materials. The proposed model describes the simultaneous application of electric and magnetic fields. Such an approach allows analysing features of multicaloric effect in bilayer FeRh/PZT structure. To verify the correctness of the developed model, the theoretical results are compared with the experimental data for the multicaloric effect in the FeRh-PZT structure.
Influence of the heat treatment on the chemical composition of the ferromagnetic Ni-Mn-In thin film
Authors: Mashirov A V , Atanova A V , Koshelev A V , Druzhinin A V , Kamantsev A P , Lyange M V , Khovaylo V V , Dilmieva E T , Koledov V V , Shavrov V G
Published: November 2019

The paper presents results of study of the dependence of the Ni-Mn-In film’s composition on the annealing parameters, data of scanning electron microscopy and energy dispersive analysis (EDX spectroscopy). The Influence of annealing of a film in vacuum on the chemical composition is shown. The content of manganese and indium decreases sharply with a rise in temperature up to 900 °C, and in a heating time up to 2 hours. The ferromagnetic Curie point in the investigated Ni-Mn-In films is observed. A decrease of the width of the ferromagnet-paramagnet transition results in the improvement of the crystallinity of the sample after annealing.
The effect of exchange-correlation potentials on magnetic properties of Fe-(Ga, Ge, Al) alloys
Authors: Zagrebin M A , Matyunina M V , Sokolovskiy V V , Buchelnikov V D
Published: November 2019

This work presents a theoretical study of magnetic properties from first-principles calculations for binary Fe100–x

Zx
type alloys (Z = Ga, Ge, Al) in concentration range of 3.125 < x < 21.875 at.%. The both, general gradient approximation and local density approximation are considered for the exchange-correlation functional. Ab initio calculations are performed for A2 and D03 crystal structures. It is shown that for local density approximation, magnetic moments are found in the better agreement with experimental ones. Using the calculated exchange coupling constants for studied compositions, Curie temperatures were estimated by means of mean field approximation. It was found that the obtained Curie temperatures are in qualitative agreement with the experiment.
Determination of saturation magnetostriction of amorphous Fe-Co-P-B ribbons: comparison of various methods
Authors: Sekirin I V , Ignakhin V S , Severikov V S , Grishin A M
Published: November 2019

We present and compare results of measurement of saturation magnetostriction constants of amorphous ribbons Fe80-x
Co
x
P14B6 (x = 23, 25, 28, 32, 40 at.%) and the reference Fe40Ni40P14B6 specimen employing Narita and Becker-Kersten methods. We also modified a strain gauge-based method to enable measurements of complete magnetic field dependence of magnetostriction coefficients.
Charge carrier concentration and structural transition temperatures in Heusler alloys Ni50Mn36Sb14-xZx (Z = Al, Ge; x = 0; 1; 2; 3; 4)
Authors: Emelyanova S M , Dyachkova T V , Tyutyunnik A P , Chistyakov V V , Domozhirova A N , Sauerzopf F , Wang R L , Yang C , Marchenkov V V
Published: November 2019

The temperature dependences of magnetization and electrical resistance of the Ni50Mn36Sb14-xZx (Z = Al, Ge; x = 0; 1; 2; 3; 4) alloys have been used to determine the structural transition temperatures (STT) such as: Ms, Mf, As and Af (temperatures of the start and finish of martensitic and austenitic transformations, respectively). Effect of various parameters (e/a, Vcell, n) on the STT was studied. Using Hall Effect the concentration of charge carriers n* was obtained and it was found that n* is not strongly correlated with a behaviour of STT, there is only a general trend with exceptions.
Magnetic properties of the non-stoichiometric TbCo2Mnx and TbCo2Nix alloys
Authors: Inishev A A , Gerasimov E G , Mushnikov N V , Terentev P B , Gaviko V S
Published: November 2019

The crystal structure, magnetic and magnetothermal properties of non-stoichiometric TbCo2Mn
x
and TbCo2Ni
x
alloys were studied. It was shown that single-phase compounds with the MgCu2-type structure exist up to a certain content of x (x < 0.4 for compounds with Mn and x ≤ 0.1 for compounds with Ni). The concentration changes of the lattice parameter, Curie temperature, magnetic moment of the 3d sublattice in TbCo2Mn
x
and TbCo2Ni
x
alloys were compared. The magnetocaloric effect in alloys were estimated using data of magnetic and heat capacity measurements.
Martensitic transformation and magnetotransport properties of Ni47Mn42In11 alloy
Authors: Kaletina Yu V , Gerasimov E G , Terentev P B , Kaletin A Yu
Published: November 2019

The structure, electrical and magnetic properties of the Ni47Mn42In11 alloy, in which the temperature of the martensitic transformation is close to room temperature and practically coincides with the Curie temperature of austenite, have been investigated. The martensitic transformation in the Ni47Mn42In11 alloy proceeds with the formation of modulated martensite type 14M. It has been established that the spontaneous transformation from martensite to austenite is accompanied by a decrease in the specific resistance of 45%. In the martensitic transformation induced by a magnetic field of 18 kOe, a negative magnetoresistance is observed, reaching ~ 15%.
MFM study of domain structure of CoNi microparticles caused by mechanical stress
Authors: Nurgazizov N I , Biziyaev D A , Bukharaev A A , Chuklanov A P
Published: November 2019

The domain structure of planar CoNi microparticles with the square shape has been studied under mechanical stress. An array of CoNi particles was formed on the surface of thin polished glass by electron beam evaporation. After studying the initial magnetization distribution, the particles were strained along one side due to bending of the substrate. It is shown that the change in the domain structure of CoNi particles depends on the degree of its tension.
Features of focusing magnetoelastic waves in YIG crystals
Authors: Bakharev S M , Borich M A , Savchenko S P
Published: November 2019

The focusing features and caustic of magnetoelastic waves in Y3Fe5O12 (YIG) crystals in the long wavelength approximation are investigated. It is shown that the interaction of phonon and magnetic subsystems leads to pronounced anisotropic properties of magnetoelastic waves. Four magnetoelastic eigenmodes are realized in the crystal, and two of them possess a focusing and caustic in the vicinity of magnetoelastic resonance point. The region of frequencies and wavenumbers of magnetoelastic waves is obtained, where the caustic can be observed. The directions of the focusing and caustic are defined.
Magnetic and magnetocaloric properties of Gd melt-spun ribbons
Authors: Svalov A , Andreev S , Arkhipov A , Kudyukov E , Neznakhin D , Larrañaga A , Kurlyandskaya G
Published: November 2019

Structural features, magnetic properties and magnetocaloric effect of pure Gd ribbons prepared by melt spinning method were carefully analyzed. The X-ray data show that there is no change in the cell parameters for the samples prepared at different copper-wheel speed. Average size of nanocrystalline grains was close to 30 nm. As compared to the bulk Gd sample, the Curie temperature was the same in the case of the ribbons. From the magnetic isotherms, the magnetic entropy change was derived using the Maxwell relation follow the standard procedure. Its value was comparable with the value of the bulk Gd. Good mechanical properties of fabricated Gd ribbon and their flexibility can be useful for design of flexible refrigerating elements.
Magnetocaloric effect in TbCo-based multilayers
Authors: Svalov A , Makarochkin I , Kudyukov E , Stepanova E , Vas’kovskiy V , Larrañaga A , Kurlyandskaya G
Published: November 2019

TbCo-based magnetic multilayers with different thicknesses of Tb-Co layers and non-magnetic spacers (Ti, Si) have been prepared by sputtering. The structure and magnetocaloric properties of these samples have been investigated. The peak value of magnetic entropy change in TbCo-based multilayers is smaller than the one previously reported for bulk counterparts. Nanostructuring leads to a table-like temperature dependence of the magnetic entropy change. It has been shown that the material of non-magnetic spacers can have a noticeable effect on magnetocaloric properties of TbCo-based magnetic multilayers.
Susceptibility and FMR in ferrite garnet epitaxial films for eddy current magneto-optical defectoscopy
Authors: Lugovskoy Nazar , Berzhansky Vladimir , Semuk Evgeniy , Shaposhnikov Alexandr
Published: November 2019

The paper presents the magnetic properties of easy plane and easy axis films on the base of Bi - ferrite garnet experimentally investigated by ferromagnetic resonance and the inductive-frequency method. The possibilities and features of the operation of these films as sensors in eddy current magneto-optical introscopy are shown on the example of visualization of linear defects in products made from aluminium alloys.
Nonlinear magneto-optical Kerr effect in Co/Pt and Co/Ta bilayer films
Authors: Kolmychek Irina A , Lazareva Kseniya A , Radovskaya Victoria V , Maydykovskiy Anton I , Temiryazeva Marina P , Temiryazev Alexey G , Shalygina Elena E , Sadovnikov Alexandr V , Nikitov Sergey A , Karashtin Evgeny A , Gusev Nikita S , Fraerman Andrey A , Murzina Tatiana V
Published: November 2019

Nonlinear magneto-optical Kerr is used to study the magnetic properties of thin bilayer films composed of cobalt and two different non-magnetic metals, platinum and tantal. Our experiments reveal different nonlinear-optical response of these two types of structures related to specific magnetic properties of Co/Ta and Co/Pt interfaces.
Magnetooptical properties of epitaxial strained ferrite films grown by MOCVD method
Authors: Telegin A V , Lobov I D , Korsakov I E , Bessonova V A , Sukhorukov Yu P
Published: November 2019

CoFe2O4 (111) epitaxial films on a single crystalline (100) ZrO2(Y2O3) substrates and non-oriented CoFe2O4 films on a metal tape were grown by the metalloorganic chemical vapour deposition (MOCVD) method. The CoFe2O4/ZrO2(Y2O3) films contain the coherent high-angle boundaries between variant domains due to the complex epitaxial distortions compared to polycrystalline state of the CoFe2O4/(metal tape) film. The structural peculiarities of films with variant structure lead to the strong anisotropy of its magnetooptical properties. Moreover a significant magnetorefractive effect, up to 1 % at 6 kOe, is revealed in both the polycrystalline and epitaxial films with variant structure in the near infrared spectral range.
Peculiarities of magneto-infrared reflectivity of nanostructured manganite films
Authors: Bessonova V , Telegin A , Nosov A , Sukhorukov Yu , Ganshina E
Published: November 2019

The electrical resistance and reflectance of unpolarized infrared radiation have been studied in the La2/3Ba1/3MnO3 films with and without a variant structure. Applying of an external magnetic field leads to appearance of magnetoreflection and colossal magnetoresistance effects with maxima near the Curie temperature of the films. The high-angle boundaries markedly enhance the electric and magnetooptical properties of nanostructured epitaxial films with the variant structure. For example, an additional low-temperature contribution to the magnetoreflection has been revealed in La2/3Ba1/3MnO3/ZrO2(Y2O3) films. This peculiarity is associated with the change of the high-frequency conductivity of the films with the variant structure due to the processes of tunnelling of spin-polarized electrons across the boundaries of structural domains far below the Curie temperature of the sample. The detection of “tunnel magnetoreflection” in the doped lanthanum manganite films could promote extension of the scope of their application in the modern optoelectronics.
Amorphous Finemet films for visualization of inhomogeneous magnetic fields
Authors: Ivanov V E , Lepalovskij V N
Published: November 2019

This paper shows that amorphous Finemet films can be used as a medium for visualization and topography of inhomogeneous magnetic fields. The intensity of magnetooptical images obtained in the geometry of the polar magneto-optical Kerr effect is proportional to the normal component of the inhomogeneous magnetic field. This allows us to construct two-dimensional topograms of the normal component of the magnetic field. The images observed in the geometry of the longitudinal magneto-optical Kerr effect carry information about the planar component of the field. The vector field of the plane component has singular points that are displayed by magneto-optical images. Applying an external homogeneous field leads to the appearance of new singular points and their motion. At special points, the plane component of the field is equal to the value of the external field. This allows you to display a planar component by recording the coordinates of specific points.
Magnetic microstructure of the Finemet-type thin films
Authors: Mikhalitsyna E , Soboleva E , Kataev V , Kulesh N , Lähderanta E
Published: November 2019

Fe73.9Cu1Nb3Si13.2B8.9 thin films were deposited on the glass substrates by means of ion-plasma radio frequency sputtering. Heat treatment at temperatures of 350, 400 and 450 °C was performed for 30 minutes in order to control thin film structural state. The X-ray powder diffraction showed that the crystallization of α-Fe(Si) nanograins took place at the temperature of 420 °C whilst the other samples stayed in the amorphous state. The magnetic microstructure of the Fe73.9Cu1Nb3Si13.2B8.9 films was discussed in the framework of random anisotropy model and law of approach of magnetization to saturation. The parameters of magnetic microstructure were determined, and relations between structure and macroscopic magnetic properties were interpreted by means of magnetic microstructure analysis.
Investigation of magnetization reversal processes in Sm(Co, Fe, Cu, Zr)7.5 magnets
Authors: Urzhumtsev A N , Andreev S V , Sharin M K , Moskalev V N , Volegov A S
Published: November 2019

The processes of magnetization reversal in isotropic and anisotropic commercial permanent magnets Sm(Co, Fe, Cu, Zr)7.5 were investigated. Features of magnetization reversal process in both textured and isotropic magnets were analyzed with δM(H) plots, magnetic susceptibility and initial magnetization curves. The magnetization reversal of Sm(Co, Fe, Cu, Zr)7.5 magnets is more complicated than that described in the coercivity model based on the domain walls pinning.
Structure and magnetic properties of (Sm1-xZrx)Fe11Ti (x=0-0.2) alloys
Authors: Ryzhikhin I , Andreev S , Semkin M , Selezneva N , Volegov A , Kudrevatykh N
Published: November 2019

Compounds with a tetragonal structure of the ThMn12 type have a high potential for creating on their basis permanent magnets with high energy density and operating temperatures up to 150 – 200 °C. In this work, samples of alloys (Sm1-x
Zr
x
)Fe11Ti (x = 0 – 0.2) obtained by the rapidly quenching method with subsequent annealing were investigated. Depending on the chemical composition and modes of synthesis in alloys (Sm1-x
Zr
x
)Fe11Ti (x = 0 – 0.2) phases of the ThMn12, α-Fe type and a small amount of ZrFe2 are formed, as well as phases with the Th2Zn17 structural type and TbCu7 at high annealing temperatures. The best magnetic properties at room temperature are realized in the alloy (Sm0.9Zr0.1)Fe11Ti after annealing at a temperature of 800 °C.
Magnetizing of Finemet-type alloys by magnetization rotation in weak fields
Authors: Kataev V A , Starodubtsev Y N , Bessonova K O
Published: November 2019

Magnetic properties of functional magnetic materials depend on the magnetization processes nature. Creation of amorphous and nanocrystalline alloys using the rapid quenching technology is the result of the latest advances in magnetic materials area. Although significantly different in structure, they show excellence properties. In this paper we will investigate the magnetization properties of the Finemet-type nanocrystalline alloys in the range of their initial permeability formation. We will show that due to low level of effective magnetic anisotropy, even in weak fields, magnetization can occur through reversible, hysteresis-free rotation of the domain’s magnetization vector.
Effect of intergrain exchange interaction on magnetic viscosity of nanocrystalline isotropic NdFeB magnets
Authors: Volegova E A , Andreev S V , Selezneva N V , Urzhumtsev A N , Volegov A S
Published: November 2019

The coefficient of magnetic viscosity, S, of NdFeB alloys with varied intergrain exchange interaction constant, K
IEI, was measured. The observed dependences of fluctuation field, H
f, on the applied field, H, are strongly correlated with K
IEI value. Cooperative magnetization reversal of single domain interacting particles leads to improve the temperature stability of permanent magnets and magnetic systems based on them.
Magnetic and magnetoimpedance properties of rapidly quenched ribbons of modified alloys based on FINEMET
Authors: Stepanova E A , Volchkov S O , Lukshina V A , Khudyakova D M , Larrañaga A , Neznakhin D S
Published: November 2019

Amorphous and nanocrystalline materials are attractive systems for basic research and technological applications. In a view of the energy economy and global warming concepts there is a request to search for soft magnetic materials for sensor applications, which do not request additional heat treatments and can be produced in most simple technological scheme. In this work the structure, static magnetic properties and magnetoimpedance (MI) were studied for FINEMET-type materials both with classic composition and for compositions with 10 % of iron substitution by Co, Ni, or Mn in initial state, i.e. without any additional heat treatmnet. The best MI responses were obtained for Mn-doped rapidly quenched ribbons.
Effect of solid solution treatment and nitrogenation on magnetic properties of Sm2+αFe17Nx powders
Authors: Kolodkin D , Popov A , Protasov A , Gaviko V , Kavita S , Prabhu D B , Gopalan R
Published: November 2019

The effect of solid solution treatment (SST) of Sm-Fe alloys and conditions of the nitrogenation on the structure and magnetic properties of the Sm2+αFe17N
x
(α = 0 ÷ 0.6) powders has been investigated. It is observed that the nitrided powders with the best hysteresis properties can be prepared from the Sm2.4Fe17 alloy after the SST at a temperature of 1050°C (5 h) and heat treatment at 525°C in a H2: N2 = 1: 1 gas mixture with a pressure of 2.5 atm. The additional ball milling of the powder enhances the coercivity to 6.4 kOe.
Magnetic properties of Co-W thin films
Authors: Lepalovskij V N , Gorkovenko A N , Nikulin K E , Moskalev M E , Kulesh N A , Vas’kovskiy V O
Published: November 2019

In this paper, the magnetic properties and structure of the Co-W films of different compositions prepared by magnetron sputtering on glass substrates without and with Ta or Ru buffer layers were investigated. The dependences of coercive force on the W content for the studied films were non-monotonic. The peak value of the coercive force of about 400 Oe was observed for the films on glass and Ta layers with W content of 8-9 at. %. The films deposited on Ru layers had a coercive force of 4 times less, and it was practically independent of the W content in a wide range from 6 to 20 at. %.
Unusual weak increase of Curie temperature and lattice parameters in Pr2Fe16.5Zr0.5
Authors: Platonov Sergey , Kuchin Anatoly , Gaviko Vasiliy , Voronin Vladimir , Yakovleva Maria
Published: November 2019

Crystal structure and magnetic and thermomagnetic properties of the Pr2Fe17-x
M
x
compounds with M = Ti, V, Cr, Zr, Nb have been studied. The change of interatomic distances is not enough to explain the growth of the Curie point and it is necessary to assume the distribution of M = Ti, V, Cr, Nb atoms over the lattice positions, similar to that previously published for the Nd2Fe17-x
M
x
compounds. It was established by neutron diffraction that Zr atoms substitute for Pr atoms in the 6c site and do not substitute for Fe atoms as might be expected from the original formula Pr2Fe16.5Zr0.5. So, the real composition of the substituted compound studied is Pr14.8(8)Zr0.52(8)Fe17. The magnetic moment of Fe atom and the magnetocaloric effect in the Pr2Fe17-x
M
x
compounds decrease with decreasing Fe content.
Magnetic properties of Cu2MnBO5 ludwigite in weak magnetic fields
Authors: Moshkina E M , Eremin E V , Velikanov D A
Published: November 2019

The results of magnetization measurements in low and ultralow (0<|H|<10 Oe) magnetic fields are presented for single-crystal Cu2MnBO5 ludwigite. An own SQUID magnetometer and AC measurement system and vibrating sample magnetometer options of PPMS were used. Magnetic properties have been investigated at different cooling modes of the sample. The features of the magnetic moment behaviour are revealed. The dissimilarity of magnetic measurement data obtained using various types of magnetometers is observed. The reasons for this are discussed.
Properties of antiferromagnetic resonance in GdB6
Authors: Semeno A V , Gilmanov M I , Shitsevalova N Yu , Demishev S V
Published: November 2019

Antiferromagnetic resonance in GdB6 exhibits a series of anomalous features such as jump of the resonance position at T
N = 15.5 K and resonance evolution to four line structure with further temperature decrease. Here we report the study of temperature behaviour of antiferromagnetic resonance modes v(H
0) in AFM phase. We analyzed v(H
0) dependencies at several temperatures T < T
N within the model of an antiferromagnet with easy anisotropy axis. In the result we have demonstrated that AFMR behaviour is determined by two following factors: (i) abrupt change of the gyromagnetic ratio γ at T
N, which remains constant (corresponding to g-factor g = 1.27) in AFM phase and (ii) jump of zero field frequency v
0 (from v
0 ≈ 0 to v
0 ≈ 20 GHz at TN
with its further growth to v
0 ≈ 35 GHz at T = 1.9 K.
NMR study of magnetic nanoparticles Ni@C
Authors: Mikhalev K N , Germov A Yu , Prokopyev D A , Uimin M A , Yermakov A Ye , Konev A S , Gaviko V S , Novikov S I
Published: November 2019

The 61Ni, 13C NMR spectra of carbon encapsulated nickel nanoparticles have been obtained. It has been shown that the cores of the particles consist of metallic nickel with face-centered cubic structure, nickel carbide Ni3C and carbon-nickel solid solution. The carbon shell of nanoparticles is a highly defective structure and close to an amorphous glassy-like carbon.
Orbital dependence of superexchange interaction in charge-ordered manganites
Authors: Gonchar L E
Published: November 2019

The current investigation is devoted to the theoretical study of orbital structure influence upon magnetic subsystem in half-doped charge-ordered manganites. The main interaction of magnetic subsystem is superexchange interaction. It forms spin-wave dispersion dependencies. Because of charge and orbital ordering, there are a lot of superexchange parameters in these compounds. That makes the dispersion rather complicated. This work clarifies some features of dispersion in terms of orbitally-dependent superexchange interactions.
Spin-wave excitations in YIG films grown on corrugated substrates
Authors: Sakharov V K , Khivintsev Y V , Stognij A I , Vysotskii S L , Filimonov Y A , Beginin E N , Sadovnikov A V , Nikitov S A
Published: November 2019

Yttrium-iron garnet (YIG) film was deposited by ion-beam sputtering on gadolinium gallium garnet (GGG) substrate with the periodical array of grooves ion-etched in its surface. Spin-wave excitations in the fabricated structure were studied by the ferromagnetic resonance (FMR) method and by the spin-wave spectroscopy. Results were compared with ones for the YIG film deposited on GGG substrate without the periodical relief.
Micromagnetic modeling of autoresonance oscillations in yttrium-iron garnet films
Authors: Teplov V S , Bessonov V D , Batalov S V , Telegin A V
Published: November 2019

One of the main problems of magnonics is finding the ways of efficiently spin waves excitation in a magnet. This paper considers the method of nonlinear amplification by phase locking of amplitude of dynamic magnetization in yttrium-iron garnet film performed by micromagnetic modeling with MuMAX3 software taking into account the real materials parameters. It is shown that the excited magnetization precession can be considered as a autoresonance phenomena. The intensity of the autoresonance in ferrimagnetic yttrium-iron garnet films has threshold dependence on the chirp rate of the exciting magnetic field.
GMR effect in nonhomogeneous magnetic field
Authors: Babaitsev G V , Chechenin N G , Dzhun I O , Kozin M G , Romashkina I L
Published: November 2019

Magnetic field sensors, based on giant magnetoresistance (GMR) effect, have a wide range of practical implementations. One of them is the use as a positioning device in different kind of actuators. Here we report on modelling of magnetoresistivity response of spin-valve (SV) based GMR structure in a various geometry of SV positioning with respect to a magnetic reference label. The model includes the magnetic label of a certain shape producing a nonhomogeneous magnetic field in 3D space and moving along a straight line in front of SV device. Different mutual label-SV positioning is considered. The reaction of micromagnetic configuration in the ferromagnetic layers and corresponding magnetoresistive effect of the SV is calculated and analyzed.
Electrical, magnetic and galvanomagnetic properties of Mn-based Heusler alloys
Authors: Semiannikova A A , Irkhin V Yu , Terentev P B , Perevozchikova Yu A , Korenistov P S , Prekul A F , Marchenkova E B , Eisterer M , Marchenkov V V
Published: November 2019

Half-metallic ferromagnets and spin gapless semiconductors are promising materials for spintronic devices since a high degree of the spin polarization of charge carriers can be realized in such materials. Spin gapless semiconductors make it possible to combine the properties of half-metallic ferromagnets with semiconductor characteristics and to perform fine tuning of the energy gap value. The Mn2
MeAl (Me = Ti, V, Cr, Mn, Fe, Co, Ni) Heusler alloys can possess such features. We studied the electrical, magnetic and galvanomagnetic properties of the Mn2
MeAl (Me = Ti, V, Cr, Mn, Fe, Co, Ni) Heusler alloys from 4.2 K to 900 K and in magnetic fields up to 100 kOe. The features in the electronic and magnetic properties of Mn2MeAl Heusler alloys were observed, which can be a manifestation of the electronic energy spectrum peculiarities with occurrence of the half-metallic ferromagnet and/or spin gapless semiconductor states.
Novel method of phase determination in neutron reflectometry using reference layer
Authors: Nikova E S , Salamatov Yu A , Kravtsov E A , Ustinov V V
Published: November 2019

We describe a novel method for phase recovery in neutron reflectometry which is based on using Gd reference layer of known thickness. Deposition of Gd reference layer at the top of unknown nanostructure allows us to reconstruct the complex reflection coefficient from the structure and to solve phase problem for magnetic nanostructures under investigation. This method makes it possible to use direct model-independent approaches (for example, Gelfand-Levitan-Marchenko approach) to obtain the scattering potential.
Magnon caustics in face centered cubic ferromagnets
Authors: Bakharev Sergey , Borich Michael , Savchenko Sergey
Published: November 2019

Caustic phenomenon in magnon propagation picture in face centered cubic lattice is investigated. The employed model takes into account the Heisenberg exchange interaction between an atom’s spin and it’s nearest and next nearest neighbors. Caustic directions are defined by exploring the corresponding dispersion relations. On the basis of face centered cubic lattice of EuS ferromagnet, such singular peculiarities are investigated for different Heisenberg exchange parameters. Magnon energy regions where the caustics can be observed are defined together with the caustic directions in characteristical crystallographic planes {100} and {110}. It was obtained that caustics can be observed if the magnon frequency is about hundreds of gigahertz, and the widths of the caustic direction regions, that are determined by the magnon frequencies, are of the order of dozens of degrees.
Spin valve based sensor elements for full Wheatstone bridge
Authors: Zavornitsyn R S , Naumova L I , Milyaev M A , Pavlova A Y , Maksimova I K , Proglyado V V , Ustinov V V
Published: November 2019

Present work deals with methods for creating opposite pinning directions in micro-objects based on a spin valve by one thermomagnetic treatment. The methods are based on the thermomagnetic treatment in spin-flop state of synthetic antiferromagnet. We use splitting the magnetic structure in spin-flop state of synthetic antiferromagnet to form opposite pinning directions in different micro-objects by one thermomagnetic treatment. The positive characteristic (dR/dH) was obtained in the two sensor elements of the full Wheatstone bridge, and the negative characteristic (dR/dH) in the other two elements.
NMR studies of interlayer boundaries in Co/Cu superlattices
Authors: Popov V V , Bannikova N S , Blinov I V , Chuprakov S A , Krinitsina T P , Milyaev M A , Ustinov V V
Published: November 2019

Effects of Cu layer thicknesses and annealing temperature on structural features of Co/Cu superlattices have been studied by nuclear magnetic resonance (NMR), electron microscopy, X-ray diffraction and X-ray reflectometry. Determination of a fraction of perfect boundaries and of Co atoms in interfaces based on NMR studies is demonstrated. Correlation of these parameters with the probability of a single electron scattering event at an interface and magnetoresistance is analyzed.
Mechanism of Electron Spin Relaxation in Spiral Magnetic Structures
Authors: Lyapilin Igor
Published: November 2019

Spin dynamics in spiral magnetic structures has been investigated. It has been shown that the internal spatially dependent magnetic field in such structures produces a new mechanism of spin relaxation.
Ion production in the 12C + 9Be interactions at GeV energies
Authors: Abramov B M , Borodin Yu A , Bulychjov S A , Dukhovskoy I A , Khanov A I , Krutenkova A P , Kulikov V V , Martemianov M A , Matsyuk M A , Turdakina E N
Published: November 2019

Differential cross sections for nuclear fragment yields at an angle of 3.5° in the fragmentation of carbon ions with an energy of 0.95 and 2.0 GeV/nucleon on a beryllium target have been measured. The momentum spectra of the fragments were used for testing predictions of few models of ion-ion interactions.