bluuebunny/crossref_metadata_2025 huggingface dataset:
The Behavior of the Ferromagnet/Wide-Band Polymer Heterostructure in Magnetic Field
Authors: Vorob’eva Natalya V. , Lachinov Aleksei N. , Kornilov V.M.
Published: June 2012

The experimental results for huge magnetoresistance in polymer/ferromagnet system have been considered. The evidences have been established for the relation of the partially spin-polarized current in the structure and the magnetoresistance events. The model of charge and spin transport of the high-conductive state of wide-band polymer film/ferromagnet heterostructure have been proposed on the base of the experimental data totality.
Spin-Waves in Stoner Ferromagnetic Phase of a Two-Dimensional Electron System
Authors: Esmailian A.H. , Kanjouri F. , Mohammadi N. , Mahloojian M.R. , Abbasi N.
Published: June 2012

We have studied the collective excitations (spin-wave energies) in the ground state of a two-dimensional (2D) electron system using the random phase approximation (RPA). To do so, we have calculated the magnetic transverse susceptibility in 2D electron system by Hartree-Fock (HF) approximation of Hubbard model at T=0 which is generally referred to as the Stoner model. The spin-waves dispersion of three-dimensional (3D) electron system due to its quadratic behavior starts from zero at q0 while our numerical results show that the spin-waves dispersion of 2D electron system starts from the value Δ, known as exchange splitting energy, even at q=0.
Spin-Injection Terahertz Radiation in Magnetic Junctions
Authors: Chigarev S.G. , Epshtein E.M. , Gulyaev Y.V. , Malikov I.V. , Mikhailov G.M. , Shofman V.G. , Zilberman P.E.
Published: June 2012

Electromagnetic radiation of 1 - 10 THz range is observed at room temperature in a structure with a point contact between a ferromagnetic rod and a thin ferromagnetic film under electric current of high enough density. The radiation is due to nonequilibrium spin injection between the components of the structure. By estimates, the injection can lead to inverted population of the spin subbands. The radiation power exceeds by orders of magnitude the thermal background (with the Joule heating taking into account) and follows the current without inertia. Efficiency of the oscillator depends strongly on the material used and quantum efficiency may exceed the unity. It means the stimulated radiation processes play an important role.
Hydrogen Absorption and Magnetic Properties of HO2Fe14BHx Hydrides
Authors: Damianova R. , Nikitin S.A. , Bezdushnyi R. , Tereshina I.S. , Tereshina E.A. , Burkhanov G.S. , Chistyakov O.D. , Iliev L.
Published: June 2012

Magnetic properties of the hydrides of an intermetallic compound Ho2Fe14B are studied in the temperature range 78 700 K. The temperature dependencies of magnetization σ (Т) are obtained under continuous control of the hydrogen content in the samples investigated. The dependence of the Curie (TC) and the spin-reorientation transition (TSR) temperatures on hydrogen pressure (P) and its concentration (x) are determined. The dependence of hydrogen concentration on pressure at constant temperatures (isotherms x (P)) in the vicinity of TC and the temperature variation of hydrogen concentration at a constant pressure (isobars x (T)) are investigated.
Rotating-Sample Magnetometer for Measuring Crystal Field Parameters
Authors: Gimaev R.R. , Spichkin Y.I. , Plyashkevich M.L. , Tishin A.M.
Published: June 2012

A method of measuring crystal field parameters by means of a rotating-sample magnetometer is presented. The measurement is performed by registering 2nd, 4th and 6th harmonics of the signal that is proportional to magnetization change due to rotation of the sample in a magnetic field. Experimentally measured temperature dependence of the amplitudes of these harmonics is used to determine the crystal field parameters within the framework of the theoretical model proposed in [. The signal is detected by a digital lock-in amplifier, while temperature is controlled by a PID controller. The sample and pickup coils are located in the bore of a Halbach permanent magnet. The measurements are fully automated. Magnitude of the expected signal was estimated. Test measurements of magnetization of the Tb single crystal along a axis (in the easy crystallographic plane a-b) in the permanent magnetic field 2.7 T at room temperature were performed. The results show that sensitivity of the instruments and the proposed design of the equipment allows us to determine crystal field parameters of heavy rare-earth metals. Testing of the control software showed that computer-device communications and execution of the software blocks are correct.
Magnetic Excitations in Locally Non-Equilibrium Media
Authors: Kabychenkov A.
Published: June 2012

The motion equation for magnetization in locally non-equilibrium media is derived. It is shown that in non-ordered media locally non-equilibrium excitations have peculiarities. There exist coupled waves of the magnetization and magnetic vector potential. Dispersion relation of the waves have frequencies corresponding to undamped waves or constant-phase damped waves and frequencies corresponding to change of real and imaginary parts of the wave number relation. Spectrum of the non-equilibrium fluctuations exhibits some pair of spin-electromagnetic modes without energy gap and electromagnetic-spin modes with energy gap branches.
The Influence of Powder Particle Size on Behavior of Hot Plastic Deformation, Structure and Magnetic Properties of Nd-Fe-B Die-Upset Magnets
Authors: Lipiec Wojciech
Published: June 2012

The influence of powder particle size on behaviour of hot plastic deformation, structure and magnetic properties of Nd–Fe–B die-upset magnets have been examined. It was found, that powder particle size strongly affected plastic properties of material during hot deformation process. Precursors made of powder with the smallest particles (d < 32 μm) shown bigger plastic resistance than those made of powder with the larger ones (32 – 88 or 88 – 350 μm). For the same pressing force and temperature, applied within hot plastic deformation process, precursors made of the smallest particle powder allowed to obtain only 56 % deformation, while the another, made of larger particle powder: 65% deformation.
Magnetic Properties of Intermetallic Compound Ti3Al with Deuterium
Authors: Patselov A. , Milyaev M.A. , Eshchenko R.
Published: June 2012

The results of magnetization measurements on Ti3Al intermetallic depending on deuterium concentration as well as structural changes caused by plastic deformation of Ti3Al deuterides are reported. It was found that the increasing of deuterium concentration leads to the Ti3Al samples magnetization growth. Magnetization of deformed deuterides decreases with the increasing deuterium concentration. Possible reasons for such magnetization behaviour are discussed.
The Dynamic Effects in Electrodeposited NiFe/Cu Wire with Preliminary Torsion
Authors: Yagmur V. , Atalay F.E. , Bayri N. , Atalay S.
Published: June 2012

Ni80Fe20/Cu composite wires were produced under torsion using electrodeposition method. The total length of the magnetic film deposited onto 50 µm Cu wire is 3 cm and the thickness of the magnetic layer is about 10 µm. All samples showed single peak in magnetoimpedance (MI) curves. The magnitude (ΔZ/Z) % are 260%, 235% and 119% for samples produced under 22.4, 44.8, 89.7 rad/m torsion values, respectively at driving frequency of 160 kHz. MI effect magnitude decreases with increasing applied torsion during the electrodeposition process. A linear change in the second harmonics of output voltage from wire ends as a function of applied magnetic field (coil-less fluxgate effect) was observed in all sample. The sensitivity of coil-less output increases with increasing torsion and maximum sensitivity was observed in the sample produced at 89.7 rad/m torsion.
Interplay between Local Electronic Structure, Crystalline Structure and Magnetic Ordering in Intermetallic Compounds Ce2Fe17−xMnx
Authors: Yaroslavtsev Alexander A. , Menushenkov Alexey P. , Grishina Olga V. , Chernikov Roman V. , Kuchin Anatoly G.
Published: June 2012

For the first time the rearrangement of cerium local environment in Ce2Fe17-xMnx(x = 0; 1; 2) intermetallics vs. Mn concentration and temperature was investigated by thespectroscopy of extended X-ray absorption fine structure (EXAFS) above K-Ce absorptionedge. At the same time under similar conditions by the spectroscopy of X-ray absorption near-edge structure (XANES) above L3-Ce absorption edge the valence state of Ce was studied. Thecorrelation is found between changes in local electronic and crystalline structure observed inCe2Fe17-xMnx and the types of magnetic states in these compounds.
Description of Substitutional Adsorption of Magnetic Ions on Metallic Surfaces with Formation of Monolayer Ferromagnetic Films Using the Spin-Density Functional Method
Authors: Klimov S.P. , Mamonova M.V. , Prudnikov Vladimir V.
Published: June 2012

At present time, a large number of experimental works have been devoted to the study of magnetic ordering in Fe, Co, and Ni ultrathin films [. The investigation of a nature of magnetism in these structures has a large fundamental interest through an observable dimensionality crossover of magnetic characteristics from three dimensional values for films with thickness d 10 nm to two dimensional values for films with thickness d 1-2 nm. It has been established that the long-range ferromagnetic order arises in films at some effective film thickness. However, the nature and regularities of this phenomenon remain not quite clear. In our paper [ it was developed in terms of the spin-density functional theory the description of influence of the temperature and ferromagnetic ordering on the adsorption of Fe, Co, and Ni transition metal ions on a nonmagnetic substrate with the formation of a submonolayer films. For case of nonactivated adsorption the conditions for the formation of magnetic monoatomic films stable with respect to island adsorption with a change in the coverage parameter θ are revealed. It was demonstrated that the inclusion of the ferromagnetic ordering substantially affects the adsorption energy and leads to its considerable increase.
Ellipsometric Study of Anisotropy Permittivity of Hexagonal Manganites RMnO3 (R = Ho, Tm, Yb)
Authors: Makhnev A.A. , Nomerovannaya L.V. , Loshkareva Natalia N. , Balbashov A.M.
Published: June 2012

The optical properties of single crystals of the hexagonal manganites RMnO3 (R = Ho, Tm, Yb) have been investigated by spectroscopic ellipsometry in the spectral range 0.6-5.0 eV. The measurements show a strong anisotropy of the diagonal elements of the dielectric tensor. It has been demonstrated that the optical absorption edge for the polarization Ec was determined by the intense band of O(2p)Mn (3d) transition centered near 1.6 eV, whereas this band for the polarization Ec was strongly suppressed and shifted toward higher energies by 0.15-0.20 eV. The spectral dependences of the ε1(E) and ε2(E) for HoMnO3, TmMnO3 and YbMnO3 single crystals were qualitatively similar. The broad absorption band at E<1.0 eV clearly appears at the energies below the fundamental absorption edge of all of study compounds. It is possible, the origin of the near-infrared ε2(E) absorption is associated with 4f-4f transitions of R3+ ions.
Bending Modes and Magnetoelectric Effects in Asymmetric Ferromagnetic-Ferroelectric Structure
Authors: Petrov Vladimir M. , Bichurin Mirza I. , Srinivasan Gopalan , Laletin V.M. , Petrov Roman V.
Published: June 2012

A model is discussed here for the resonance enhancement of magnetoelectric (ME) interactions in ferrite-piezoelectric bilayers at frequencies corresponding to bending oscillations. The thickness dependence of stress, strain and magnetic and electric fields within the sample are taken into account so that the bending deformations could be considered in an applied magnetic or electric field. The boundary conditions corresponding to bilayers that are free to vibrate at both ends, or simply supported at both ends, or fixed at one end are considered. The explicit expressions for ME voltage coefficients are derived by way of exact solution of electrostatic, magnetostatic and elasto-dynamic equations for thin plate and disk-shaped bilayers. The model is applied to a specific case of nickel and lead zinconate titanate (PZT) bilayer. Theoretical ME voltage coefficients versus frequency and PZT to nickel thickness ratio profiles are in excellent agreement with data.
Spatially Modulated Antiferromagnetic Structures in Multiferroic with Biaxial Anisotropy
Authors: Kulagin N.E. , Popkov A.F. , Zvezdin A.K. , Soloviov S.V.
Published: June 2012

We report on possible types of spatially modulated antiferromagnetic structures in the biaxial multiferroic and their stability depending on the ratio of the magnetic anisotropy and flexomagnetoelectric interaction parameters.
Importance of Thermally Induced Magnetic Excitations in First-Principles Simulations of Elastic Properties of Transition Metal Alloys
Authors: Abrikosov Igor A. , Ekholm Marcus , Ponomareva Alena V. , Barannikova Svetlana A.
Published: June 2012

We demonstrate the importance of accounting for the complex magnetic ground state and finite temperature magnetic excitations in theoretical simulations of structural and elastic properties of transition metal alloys. Considering Fe72Cr16Ni12face centered cubic (fcc) alloy, we compare results of first-principles calculations carried out for ferromagnetic and non-magnetic states, as well as for the state with disordered local moments. We show that the latter gives much more accurate description of the elastic properties for paramagnetic alloys. We carry out a determination of the magnetic ground state for fcc Fe-Mn alloys, considering collinear, as well as non-collinear states, and show the sensitively of structural and elastic properties in this system to the detailed alignment between magnetic moments. We therefore conclude that it is essential to develop accurate models of the magnetic state for the predictive description of properties of transition metal alloys.
Ni-Mn-In Heusler Alloy Thin Films Grown by Pulsed Laser Deposition
Authors: Grunin A. , Goikhman A.Y. , Rodionova V.
Published: June 2012

We report on the results of the magnetic and structure properties investigation of Heusler alloy films. Ni-Mn-In thin films were formed by pulsed laser deposition. Stoichiometry was varied and controlled by co-deposition technique. The different deposition conditions and influence of the annealing temperature on the film composition were investigated using Auger electron spectroscopy and Rutherford backscattering spectrometry. The optimal annealing temperature was found to be 620 K. The set of the films deposited on the oxidized Si (100) substrate at room temperature and annealed at 620 K was investigated using X-ray diffractometry at room temperature and Vibrating sample magnetometery at low temperatures. The crystal structure was found to be a mixture of austenitic and martensitic phases at room temperature. Decreasing of Curie temperature from 270 K to 250 K with the decreasing of In concentration from 20 at % to 15 at % was observed.
The Effect of Structural State on Magnetic and Magnetocaloric Properties of Micro-and Nanocrystalline Gd
Authors: Nikitin S.A. , Smarzhevskaya A.I. , Kaminskaya T.P. , Semisalova A.S. , Popov V.V. , Tereshina I.S. , Burkhanov G.S. , Chistyakov O.D. , Dobatkin S.V.
Published: June 2012

The effect of micro-and nanocrystalline structural state on magnetic properties and magnetic entropy (ΔSM) of Gd is investigated. The marked influence of severe plastic deformation on ΔSM is demonstrated.
Numerical Simulation of Magnetic Cooling Cycles
Authors: Skokov Konstantin , Karpenkov Alexey , Pastushenkov Yury G. , Gutfleisch Oliver
Published: June 2012

A model for Brayton cooling cycles used in magnetic refrigeration near room temperature was developed. This model was used to calculate a theoretical limit of temperature span and cooling power. The cooling power was calculated for single and double Brayton cooling cycles with Gd as the working body. The obtained results clearly demonstrate the functional ranges of Bryton-cycle refrigerators.
The Magnetocaloric Effect in Two-Phase Y-Fe Nanocrystalline Alloys
Authors: Karpenkov Dmitriy , Karpenkov Alexei Y. , Skokov Kostantin P. , Semenova Elena M. , Smirnov Roman F. , Airiyan Eduard , Arefev Arthur I. , Pastushenkov Yury G.
Published: June 2012

Synthesis of nanocomposite based on binary compound and determination of dependence between the values of magnetocaloric effect (MCE) and the grain size of such specimens are the purposes of this work. The results of the investigation in microcrystalline and nanocrystalline samples Y25Fe75 and Y35Fe65 alloys show, that reduction of the grain size down to 80-100 nanometers on nanocrystalline samples of Y25Fe75 and Y35Fe65 alloys leads to increasing of value of MCE by 20-25 % from comparison with values on microcrystalline samples. It can be explained by intergrain exchange interaction in nanocrystalline alloys.
Specific Heat of MnCoGe Type Compounds at Martensitic Phase Transitions
Authors: Markin P.E. , Mushnikov N.V. , Proshkin A.V. , Belyaev S.V.
Published: June 2012

The X-ray diffraction and specific heat measurements have been performed for the ferromagnetic compounds (MnCo)1-xGe within the concentration range 0.02 x 0.035. The compounds possess the hexagonal Ni2In-type structure at elevated temperatures, while for the composition with x = 0.02 and 0.03 a spontaneous martensitic-type transition to the orthorhombic TiNiSi-type phase occurs at 283 and 221 K, respectively. We studied the entropy changes associated with the first-order structural transition and estimated the changes in magnetic, lattice, electronic entropies.
Monte Carlo Study of the Magnetic and Magnetocaloric Properties of La1-xCaxMnO3 (x = 0.33 and 0.5)
Authors: Pavlukhina O.O. , Buchelnikov Vasiliy D. , Sokolovskiy V.V. , Zagrebin M.A.
Published: June 2012

In our work the temperature dependencies of magnetization, entropy changes, and the Curie temperature (TC) of La1-xCaxMnO3 (x = 0.33 and 0.5) were investigated using Monte Carlo method and Heisenberg model. In our simulation, magnetic Mn3+ and Mn4+ ions are described by classical Heisenberg spins, while oxygen, lanthanum and calcium ions are considered as non-magnetic. The Mn magnetic ions are distributed on a simple cubic lattice according to the perovskite structure of the manganite. The theoretical Curie temperatures and magnetocaloric values are in a good agreement well with experimental data.
Spectral Domain Magneto-Optical Magnetometry
Authors: Mansurova M. , Kolokoltsev O.V.
Published: June 2012

In this work we present a new concept for measuring high intensity pulsed magnetic fields (h (t)) through the spectral analysis of spin excitations in a saturated yttrium-iron garnet (YIG) thin film grown on a gadolinium gallium garnet (GGG) substrate. The spectrum of spin excitations, generated in the sample by picosecond h (t), was determined with the help of a magnetooptical (MO) Faraday probe in the guided wave regime of lightwave propagation. This technique, compared to the standard MO cells, allows one to avoid saturation effects because the amplitude of h (t) is measured in the frequency domain, and allows us to realize the analysis in real time taking advantage of strong a MO signal.
The Analysis of the Magnetorefractive Effect in La 0.7Ca0.3Mno3: Thin Films and Single Crystals
Authors: Yurasov A.N. , Bakhvalova T.N. , Telegin A.V. , Sukhorukov Yu.P. , Granovsky A.B.
Published: June 2012

Recently, it has been shown that the magnetorefractive effect in reflection and transmission modes in La0.7Ca0.3MnO3 manganite thin films and single crystals can reach several percents for single crystals and up to 20-40% for thin films in the middle infrared spectral range near the Curie temperature. In the present paper, to explain these data we used the effective medium approach and supposed that La 0.7Ca 0.3MnO3 manganites consist of low and high resistivity phases with volume fractions depending on an applied magnetic field. It is shown that the magnetorefractive effect spectra strongly depend on magnetoresistance and optical properties of manganites in the infrared range.
Investigation of Multicritical Phenomena in Complex Models of Magnetics by Monte-Carlo Methods
Authors: Murtazaev Akai K. , Ibaev J.G.
Published: June 2012

The anisotropic Ising model with competing interactions is investigated in wide temperature range and |J1/J| parameters by means of Monte-Carlo methods. Static critical exponents of the magnetization, susceptibility, heat capacity, and correlation radius are calculated in the neighborhood of Lifshitz point. According to obtained results a phase diagram is plotted, the coordinates of Lifshitz point are defined, and a character of multicritical behavior of the system is detected.
Structural and Magnetic Properties of the Periodic [Fe(5nm)/V(5nm)]10 and [Fe (3nm)/V(3nm)]20 Systems
Authors: Khaydukov Yu. N. , Perov Nikolai S. , Borisov M. M. , Mukhamedzhanov E. Kh. , Csik A. , Zhernenkov K. N. , Nikitenko Yu. V. , Aksenov V. L.
Published: June 2012

Results of the study of the structural and magnetic properties of periodic Fe/V heterostructures with periods D = 9.4nm and D = 6.3nm are present. The study has shown that ferromagnetic islands are formed on the interfaces of Fe and V. These islands have different magnetic properties as sub-layers of pure iron. Islands in the sample with the period D = 9.4 nm have anisotropic shape, which leads to the anisotropy of magnetic properties.
Current-Phase Relation in Josephson Junctions with Complex Ferromagnetic/Normal Metal Interlayers
Authors: Bakurskiy S. V. , Klenov N. V. , Karminskaya T. Yu. , Kupriyanov M. Yu. , Kornev V. K.
Published: June 2012

In the frame of Usadel equation the two-dimensional nonlinear boundary problem for heterostructures with complex ferromagnetic (F)/normal metal (N) interlayer has been solved numerically for arbitrary values of electrodes spacing L, thickness dN and dF of N and F films. We calculate the current-phase relations for ramp-type S-NF-S and overlap-type SFN-FN-NFS junctions. We have found the range of parameters providing an opportunity for realization of Josephson φ-junction based on the considered structures.
Superconducting Critical Temperature and Magnetic Inhomogeneities in Superconductor/Ferromagnet/Superconductor Trilayers
Authors: Prischepa Serghej L. , Kushnir V. N. , Cirillo C. , Attanasio C. , Kupriyanov M. Yu.
Published: June 2012

The effect of ferromagnetic layer inhomogeneity on the superconducting resistive transition in Superconductor/Ferromagnet/Superconductor (S/F/S) trilayers is studied. The critical temperature, Tc, and the resistive transition shape versus the F layer thickness, dF, in Nb/Cu0.41Ni0.59/Nb and Nb/Pd0.81Ni0.19/Nb trilayers were analyzed. It is shown that the Tc(dF) dependence is sensitive to the Ni concentration variation along the F layer for thickness of dF corresponding to the π-superconducting state and to the 0-π crossover thickness.
Phase Transition in Frustrated Heisenberg Antiferromagnet on a Triangular Lattice with Next-Nearest Neighbor Interactions
Authors: Murtazaev A.K. , Ramazanov M.K. , Badiev M.K.
Published: June 2012

We study the critical behavior of three-dimensional antiferromagnet Heisenberg model with nearest-neighbor (J) and next-nearest-neighbor (J1) interactions by the Monte Carlo method using a high-effective replica exchange algorithm. Here is calculated a full set of main static critical exponents for values R =J1/J= 0.0; 0.025; 0.05; 0.075; 0.1; 0.115 using the finite-size scaling theory. A phase diagram of dependency of the critical temperature on a relation between nearest-neighbor and next-nearest-neighbor R is plotted.
The Influence of Surface Active Substances Various Concentrations on Goethite Nanoparticles Magnetic Properties
Authors: Novakova A. A. , Antonov A. N. , Gendler Tatiana S. , Kolesnikov E. A. , Puzik I. I. , Levina V. V.
Published: June 2012

Goethite nanopowder was prepared in the process of chemical precipitation of iron salt (FCl3) and alkali (NaOH) with addition of various surface active substances (SAS): cation-active cetylpyridinium chloride (CPC), anion-active sodium dodecyl sulphate (SDS) and complexon EDTA. The concentrations of SAS were 0.3% and 1%. It could be deduced from TEM data that these SASes unambiguously influence sizes of prepared goethite particles, compared with samples, obtained without SAS: in case of adding 1% SDS and EDTA significant crystal growth takes place. To explain this situation the study of magnetic characteristics and phase composition of obtained nanoparticles was carried out using Mossbauer spectroscopy and thermomagnetic analysis (TMA). It was suggested, that different organic Fe3+- complexes formed on goethite surface under SAS influence take part in the goethite crystallization process.
Influence of Permalloy Layer and Ti Spacer Thicknesses on Magnetic and Magnetoresistive Properties of Fe19Ni81/Ti/Tb-Co Films
Authors: Kulesh N. A. , Balymov K. G. , Sorokin A.N. , Vas’kovskiy V.O.
Published: June 2012

Fe19Ni81/Tb35Co65 magnetic films having unidirectional anisotropy were investigated with focus on the influence of the Fe19Ni81 layer and Ti spacer thicknesses on magnetic and magnetoresistive properties of the multilayered structures. Principles of the optimization of the properties of magnetoresistive multilayers with unidirectional anisotropy were proposed.
Relaxation Mössbauer Spectroscopy of Iron Oxides Nanoparticles in Superferrimagnetic Regime
Authors: Cherepanov V. M. , Chuev M. A. , Polikarpov M. A. , Shishkov S. Yu.
Published: June 2012

Film composites based on magnetite Fe3O4 nanoparticles in the polyvinyl alcohol (PVA) matrix and the dried ferrofluid ARA-250 (Chemicell GmbH, Germany) were studied at temperatures 78-300 K by Mössbauer spectroscopy and magnetic measurements in magnetic fields H < 5 kOe. The Mössbauer spectra taken in magnetic fields show essential restoration of the magnetic hyperfine structure characteristic for the nanoparticles. The experimental Mössbauer spectra have been analyzed within the recently developed three-level [ and multi-level [ relaxation models of magnetic dynamics in an ensemble of single-domain particles. These models take into account the precession and diffusion of particles uniform magnetization as well as the particles size distribution and interparticle interactions.
The Features of the Structure and Magnetic Properties of Co-SiO2, Co-Al2O3 Composite Films with Tunneling Magnetoresistance Effect
Authors: Gorkovenko A.N. , Vas’kovskiy V.O. , Lepalovskij V.N. , Shchegoleva N.N.
Published: June 2012

In the present work, we have studied the structural, magnetic and magnetoresistive properties of Cox(SiO2)100-x and Cox(Al2O3)100-x composite thin films, obtained by magnetron co-sputtering of metallic and insulator targets. It was shown by transmission electron microscopy and by temperature and field dependences of the magnetization that the films have a fine granular structure. For a wide range of compositions an adequate description was possible in frame of the model of homogeneous non-interacting superparamagnetic hexagonal lattice Co particles. Magnetoresistive sensor prototypes were designed on the base of an optimized magnetoresistive Co50(Al2O3)50 composite films
Anomalies of Elastic Properties at Phase Transitions in Rare Earth Cobaltites RBaCo4O7 (R = Y, Er - Lu)
Authors: Kazei Z.A. , Snegirev V.V. , Kozeeva L.P. , Kameneva M.Yu.
Published: June 2012

Elastic properties of rare-earth cobaltites RBaCo4O7 (R = Y, Er - Lu) are studied in the temperature range (4.2 - 300) K. Significant softening of Youngs modulus for Lu-and Yb-cobaltites is found at temperature decrease, showing an instability of the crystal structure and accompanying by a reverse jump at the structural phase transition. Softening and jump at phase transition decrease more than by the order of value, while the transition temperature Ts and hysteresis dTs enlarge from Lu-to Tm-and Er-compounds. Smooth and weak elastic anomaly at the magnetic phase transition is found resulting from low dimension and frustration of exchange interactions in the Co subsystem in most of the rare-earth cobaltites studied.
Magnetization Correlations and Random Magnetic Anisotropy in Nanocrystalline Films Fe78Zr10N12
Authors: Komogortsev S.V. , Iskhakov Rauf S. , Sheftel E.N. , Harin E.V. , Krikunov A.I. , Eremin E.V.
Published: June 2012

The quantitative analysis of static ferromagnetic correlations in nanocrystalline films Fe78Zr10N12was performed by two methods: the correlation magnetometry technique and magnetic force microscopy. The data, obtained by both methods, prove to be in good agreement.
Characteristics of the Periodic Fine Structure in Domain Walls in Vacuum-Deposited Films
Authors: Sagdatkireeva M.B. , Rumyantseva V.V. , Khasanov N.A.
Published: June 2012

The characteristics of the periodic fine structure in domain walls in oblique-evaporated films of quantum-well (QW) thickness with an easy-magnetization axis inclined with respect to the normal to the film plane has been studied. It is pointed out that the self-organization of domain structures is related to the quantum character of the cooperative phenomenon of ferromagnetism [. The spectrum of magnetoelastic waves has been calculated for films of iron type.
Bias-Current and Optically Driven Transport Properties of the Hybrid Fe/SiO2/p-Si Structures
Authors: Volkov Nikita V. , Eremin E.V. , Tarasov A.S. , Varnakov S.N. , Ovchinnikov S.G.
Published: June 2012

Pronounced optical-and bias-current-sensitive features of the transport properties of a Fe/SiO2/p-Si hybrid structure in planar geometry at temperature variation are investigated. Comparative analysis of two Fe/SiO2/p-Si samples, one with a continuous Fe film and the other with two electrodes formed from a Fe layer and separated by a micron gap, shows that these features are due to the MIS transition with a Schottky barrier near the interface between SiO2 and p-Si. Resistance of such a MIS transition depends exponentially on temperature and bias. In the structure with a continuous ferromagnetic film, the competition between conductivities of the MIS transition and the Fe layer results in the effect of current channel switching between the Fe layer and a semiconductor substrate. Within certain limits, this process can be controlled by a bias current and optical radiation. The mechanism of the optical effect is photogeneration of electron-hole pairs in the semiconductor substrate near its boundary with SiO2 layer.
The Effect of Dopants on Magnetic Properties of the Ordered Fe65-xAl35-yMx,y (Mx,y=Ga,B,V; X,Y=5,10) Alloys
Authors: Voronina E. , Yelsukov Eugene P. , Korolyov A.V. , Klauss H.H. , Dellmann T. , Granovsky S.A.
Published: June 2012

The results of X-ray diffraction, complex in-field (up to 9 T) and temperature (5300 К) Mössbauer and magnetometric studies of the ordered Fe65Al35-хMх (M=Ga, B; x=0,5,10) and Fe65-хVxAl35 (x=5,10) alloys are presented. Analysis of the magnetometry studies shows that the systems Fe65Al35 и Fe65Al35-хGaх (x=5, 10) are characterized by two different magnetic states with essentially distinguishing hysteresis loops and AC susceptibility values. The temperature and external magnetic field values inducing the transition from one magnetic state to another are higher in the Ga-doped alloys than in the reference Fe65Al35 alloy. The boron addition transforms the magnetic state of the initial alloy Fe65Al35 into a ferromagnetic one exhibiting high magnetic characteristics. Substitution of V for Fe in the ternary alloys Fe65-хVxAl35 results in reduction of magnetic characteristics and collapsing of 57Fe hyperfine magnetic filed.
Peculiarities in Optical and Magneto-Optical Spectra of GaMnSb Layers Grown by Laser Ablation
Authors: Gan'shina E.A. , Golik L.L. , Kovalev V.I. , Kun’kova Z.E. , Temiryazeva M.P. , Danilov Y.A. , Vikhrova O.V. , Zvonkov B.N. , Novikov A.I. , Vinogradov A.N.
Published: June 2012

Optical and magneto-optical properties of GaMnSb layers fabricated on GaAs (001) substrates by laser ablation technique were studied using spectral ellipsometry (E =1.24-3.25 eV) and the transversal Kerr effect (TKE) (E = 0.5 4.2 eV) as well as atomic and magnetic force microscopy. Spectra of the constituents of the diagonal components of the permittivity tensor as well as TKE depended substantially on the layer fabrication conditions. At room temperature a strong resonant band was observed in the TKE spectra for the GaMnSb layers with low Mn content in the energy range E 0.5-1.5 eV. This resonant TKE band was explained by excitation of surface plasmons in MnSb nanoclusters, which arose during the growth of the layers. In the energy region E >1.5 eV the TKE spectra were related to interband transitions in MnSb inclusions.
Insulator-Metal Transition in Diluted Magnetic Semiconductor Pb1-x-ySnxVyTe under Pressure
Authors: Skipetrov E.P. , Golovanov A.N. , Kovalev B.B. , Skipetrova L.A. , Mousalitin A.M. , Slynko E.I. , Slynko V.E.
Published: June 2012

The galvanomagnetic properties in weak magnetic fields (4.2T300 K, B0.07 T) as well as Shubnikov-de Haas effect (T=4.2 K, B7 T) in the single crystal Pb1-x-ySnxVyTe (x=0.20, y0.01) under hydrostatic compression up to 15 kbar have been investigated. It is shown that under pressure the decrease of activation energy of vanadium deep level, n-p-inversion of the conductivity type at low temperatures and insulator-metal transition take place. In the metallic phase sharp increase of the Hall mobility and appearance of Shubnikov-de Haas oscillations at helium temperature are observed. The pressure coefficient of vanadium level energy is determined and the diagram of the electronic structure rearrangement for Pb1-x-ySnxVyTe under pressure is proposed.
TE-Wave Propagation through 2D Array of Metal Nanocylinders
Authors: Ivanov A.V. , Shalygin A.N. , Sarychev Andrey K.
Published: June 2012

The plasmonic system consisting of two-dimensional periodic array of silver cylindrical nanoparticles is considered. The light reflection and transmittance, calculated for various frequencies, show the resonance behavior. Excitation of plasmons in the array of nanorods is studied. The resonance electromagnetic modes are strongly localized around the cylinders and local electric field is much enhanced.
Magnetic Properties and Magnetoimpedance of Electroplated Wires
Authors: Kurlyandskaya G.V. , Jantaratana P. , Bebenin N.G. , Vas’kovskiy V.O.
Published: June 2012

Magnetic properties and giant magnetoimpedance (GMI) of CuBe/Fe20Co6Ni74 electroplated wires was studied for frequency of 1 MHz and the amplitude of the driving current of 20 mA with focus on the development of magnetic field detectors of particular types. The possibility of quantitative ferrofluid concentration measurements was demonstrated. GMI of electroplated wire can be useful for the study of the dynamic properties of the ferrofluid. GMI of the electroplated wires in the non-uniform field created by the permanent magnet was studied in the configuration adapted for automatic control lines, machinery control, and positioning systems.
Analysis of In-Plane Anisotropy Influence on Nonlinear Magnetization Oscillations Accompanying 90° Pulsed Reversal Processes in Real Ferrite-Garnet Films
Authors: Kolotov O.S. , Matyunin A.V. , Nikoladze G.M. , Polyakov P.A.
Published: June 2012

The possibility of suppression of gyroscopic magnetization oscillations by increasing an effective in-plane anisotropy field is discussed. It is shown that the presence of biaxial anisotropy in real films with the effective field ranging from 10 to 70 Oe should not cause any difficulties at suppressing the oscillations.
Waveguide Properties of Planar Structures Based on the Left-Handed Media
Authors: Sannikov D.G.
Published: June 2012

Analysis of dispersion relations for guided modes in various types of planar three-layer structures containing isotropic layers based of left-handed media (LHM) is carried out. The conditions are studied for the existence of bulk and surface TE and TM modes. The waveguide resonators with distributed feedback are proposed, implemented in a structure with LHM and amplifying guiding layer.
Features of Magnetic Properties and FMR of CoFeZr/Si Layered Nanosystems due to their Inner Structure
Authors: Chekrygina Ju. , Devizenko A. , Kalinin Y. , Lebedeva E. , Shipkova I. , Sitnikov A.V. , Syr’ev N. , Vyzulin S.
Published: June 2012

Static magnetic properties, ferromagnetic resonance (FMR) and glancing angle X-ray diffraction spectra (GAXRD) of CoFeZr (tm)/Si (tSi) in multilayer nanosystems were investigated for two groups of the samples characterized by tm = 2 3 nm, tSi = 0.5 5 nm and by tm = 7 12 nm, tSi = 5 13 nm. A computer simulation of GAXRD spectra of multilayer interference structures has been performed taking into account the possibility of silicides formation at metal-Si interfaces. Matter of discussion is the layer and interlayer thickness below which a resonance response corresponds to that of an effective medium rather than of an individual magnetic layer.
SAXS Studies of Ultrasonicated Dispersions of Biomineral Particles Produced by Klebsiella oxytoca
Authors: Anghel L. , Balasoiu Maria , Ishchenko L.A. , Stolyar S.V. , Rogachev A.V. , Kurkin T.S. , Kuklin A.I. , Raikher Yu.L. , Iskhakov R.S. , Arzumanian G.M.
Published: June 2012

A small angle X-ray scattering experiment was performed on ferrihydrite nanoparticles produced by bacteriumKlebsiella oxytoca. Structural investigations of ultrasonicated samples of different concentrations of water-dispersed particles were performed. Model calculations and fitting procedures revealed scattering objects of an elongated shape of 6.73±0.16 nm radius of gyration.
Anisotropic Silicone Rubber Based Magnetorheological Elastomer with Oil Silicone and Iron Microparticles
Authors: Bica I. , Balasoiu Maria , Kuklin A.I.
Published: June 2012

Results on anisotropic magnetorheological elastomers magnetoelasticity are presented and discussed. In the dipole approximation, and considering the MRE as a continuous linear body, the effects of magnetic field on its main elastic properties (linear deformations and Young module) are investigated. Experimental evidences that the compression of the cylindrical bar is influenced by the intensity of the longitudinal magnetic field and the Young module of the MRE sample increases with the intensity H of the longitudinal magnetic field are obtained and the results discussed.
Extension of the Working Temperature Range of Magnetic Fluid Susceptibility Measurements
Authors: Lebedev A.V. , Lysenko S.N.
Published: June 2012

Tests have been carried out to measure the temperature dependence of static susceptibility of a magnetic fluid stabilized with polypropylene glycol (PPG) in propanol, ethyl ether and propylene oxide. The use of propylene oxide provides the widest temperature range for measurements of fluid susceptibility. The coagulation stability of the PPG-stabilized magnetic fluid against ethylene glycol and 1,4-butylene glycol is investigated. It has been shown that ethylene glycol can be used to separate PPG magnetic fluid into fractions. The fluid separation begins as soon as the volumetric fraction of ethylene glycol exceeds 30%. Butylene glycol is unsuitable for fractionation but can be used to remove excess surfactant - PPG.
Dynamics of a Dielectric Microdrop Suspended in a Magnetic Fluid in Electric and Magnetic Fields
Authors: Tkacheva Elena , Zakinyan Arthur , Dikansky Yury
Published: June 2012

The dynamics of a microdrop of dielectric liquid suspended in a magnetic fluid under the action of electric and magnetic fields is studied experimentally. With increasing electric field, the deformation of droplets into oblate spheroid, toroid and curved toroid was observed. At the further increase in the electric field, the bursting of droplets and electrorotation were also investigated. The influence of an additional magnetic field on the droplet dynamics was studied.
Non-Equilibrium Magnetization of a Dilute Suspension of Brownian Magnetic Particles
Authors: Tyatyushkin Alexander
Published: June 2012

The influence of the inertial effects on the non-equilibrium magnetization of a suspensionof Brownian magnetic particles in a viscous liquid in a varying uniform magnetic field is theoreticallystudied. Themagnetization of the suspension is calculated. The heat generation power density is foundas a function of the frequency of the applied magnetic field.
Incommensurate Spin-Density Wave in Two-Dimensional Hubbard Model
Authors: Timirgazin M.A. , Arzhnikov Anatoly K. , Vedyayev A.V.
Published: June 2012

We consider the magnetic phase diagram of the two-dimensional Hubbard model ona square lattice.We take into account both spiral and collinear incommensurate magnetic states.The possibility of phase separation of spiral magnetic phases is taken into consideration as well.Our study shows that all the listed phases appear to be the ground state at certain parametersof the model. Relation of the obtained results to real materials, e.g. Cu-based high-temperaturesuperconductors, is discussed.
Nucleation and Development of Clustered State in La1-xSrxCoO3 and La1-xCaxCoO3 Single Crystals at x=0.15
Authors: Lazuta A.V. , Ryzhov V.A. , Kurbakov A.I. , Khavronin V.P. , Molkanov P.L. , Mukovskii Ya.M. , Pestun A.E. , Privezentsev R.V.
Published: June 2012

Results of structural neutron diffraction study and data on the transport and magnetic properties (the linear and nonlinear (second and third order) susceptibilities) are presented for the La1-xSrxCoO3 and La1-xCaxCoO3 at x = 0.15 single crystals. It is founf that these compounds are insulators and exhibit the rhombohedral R3-c space group. According to the magnetic measurements, the development of the ferromagnetic (F) clustered state proceeds into three stages. On cooling, during the first stage, the F clusters nucleate at the preferential sites that are likely produced by variation in oxygen and doping stoichiometry. The second stage is characterized by sharp increasing the concetraion of the isolated F clusters on cooling. This is the process of the homogeneous nucleation. A coalescence of the isolated F clusters into some large-scale complexes containig some ammount of the domains is associated with the third stage. Note that it is the typical behavior observed at a first order phase transition. The data allow one to determined reliably the temperature boundaries of the stages.
Infrared and X-Ray Absorption Spectra of Cu2O and CuO Nanoceramics
Authors: Mostovshchikova Elena V. , Gizhevskii Boris A. , Loshkareva Natalia N. , Galakhov Vadim R. , Naumov Sergey V. , Ponosov Yurii S. , Ovechkina Natalia A. , Kostromitina Natalia V. , Buling Anna , Neumann Manfred
Published: June 2012

We present the results of the study of middle infrared absorption (MIR) and X-ray absorption (XAS) spectra of nanostructured CuO and Cu2O ceramics prepared by the high pressure torsion method from coarse-grain oxide powders. We have found that the MIR bands at ~140 meV in CuO and Cu2O nanoceramics are associated with the presence of Cu+ and Cu2+ ions, respectively. X-ray absorption spectra indicate an appearance of extra Cu2+ and Cu+ ions in nanoCu2O and nanoCuO ceramics, respectively.
Investigation of Phase Transitions in the Site-Diluted Three-Dimensional Potts Model
Authors: Murtazaev A.K. , Babaev A.B.
Published: June 2012

The phase transitions and critical phenomena in three-dimensional (3D) site-diluted 3-and 4-state Potts models is investigated by Monte-Carlo method based on the highly efficient Wolff algorithm. The systems with linear sizesL=20-44 at spin concentrationsp=1.00, 0.95, 0.90, 0.80, 0.70, 0.65 are explored. The second-order phase transition is shown to occur in the three-dimensional 3-state Potts model with nonmagnetic impurities. In the 4-state Potts model there are observed first-order phase transitions in weakly diluted state, when the model is strongly diluted the first-order phase transitions change to the second-order one. On the basis of the finite-size scaling theory static critical exponents of specific heatα, susceptibilityγ, magnetizationβ, and exponent of correlation radiusνfor the systems under study are calculated.
Oxygen Isotope Effect in Ordered PrBaMn2O6
Authors: Taldenkov A.N. , Babushkina N.A. , Inyushkin A.V. , Kalitka V.S. , Kaul A.R.
Published: June 2012

The oxygen isotope effect in ordered half-doped manganite PrBaMn216-18O6 has been investigated. Real and imaginary parts of ac magnetic susceptibility, dc magnetization and magnetoresistance were measured at temperatures from 4.2 to 320 K in applied magnetic field up to 35 kOe. Substantial increase of charge ordering (CO) transition temperature TCO under oxygen isotope substitution 16O 18O and small decrease of ferromagnetic (FM) transition temperature TFM were found. Small systematic shift of ferromagnetic transition temperature in oxygen reduced manganite PrBaMn216 18O5 is also considered. The obtained results are compared with those observed in other manganites demonstrating the large isotope effect.
Magnetoacoustic Investigation of the Jahn-Teller Effect in Chromium Doped ZnSe Crystal
Authors: Gudkov V.V. , Bersuker I.B. , Yasin S. , Zherlitsyn S. , Zhevstovskikh I.V. , Mayakin V.Y. , Sarychev M.N. , Suvorov A.A.
Published: June 2012

Ultrasonic investigation of ZnSe:Cr2+crystal was carried out at low temperatures in magnetic field applied along the wave vector. The observed anomalies in magnetic field dependences of attenuation and wave number evidence for existence of resonant transitions between the energy levels of the Jahn-Teller tetrahedral complex CrSe4.
Spin Waves in Multilayers with Different Magnitudes of the Magnetization, Exchange, and Anisotropy
Authors: Ignatchenko V.A. , Tsikalov D.S.
Published: June 2012

The spin-wave spectrum in one-dimensional magnon crystals periodic superlattices (SLs) is investigated for the rectangular and sinusoidal modulation profile of the material parameters. The dependences of band gaps in the spectrum on both the difference of the magnetic parameters in adjacent layers and the ratio of the layer thicknesses are calculated.
Use of Semi-Dipole Magnetic Field for Spacecraft Radiation Protection
Authors: Ahmadi Tara
Published: June 2012

There are various methods to shield spacecraft from energetic particles, like one based on the usage of the permanent magnets. At the same time this method is not perfect; it only suggests low intensity magnetic field because of neglecting galactic cosmic radiation effects on human body. In this paper, hyper thin rings as a shield for spacecraft are suggested. Although these rings are lighter than permanent magnets, their ability to protect spaceship with a safe and high intensity magnetic field is higher than the magnets.
Magnetohydrodynamic Thermochemotherapy and MRI of Malignant Tumorigenesis
Authors: Brusentsov N.A. , Pirogov Y.A. , Polyanskiy V.A. , Anisimov N.V. , Golubeva I.S. , Gulyaev M.V. , Nikitin M.P. , Yuryev M.V. , Brusentsova T.N. , Nikitin P.I.
Published: June 2012

Citric-ferrite sol (CFS) has been synthesized and successfully tested as MRI negative contrast preparation for revealing primary tumors, and also invasions and metastases at the tumor relapses. Magnetohydrodynamic thermochemotherapy (MTC) by Cysplatin (CP), Mitoxantron (MX), Melphalan (MP) combined with CFS, which were carefully monitoring in vivo and quantified by an electronic detector, improved results of cancer treatment. At various stages of oncogenesis, MTC with CFS at a dose of 62 mg Fe/kg combined with chemotherapeutic drugs was performed at +48º C for 30 min. While such MTC, treatment of ~30 mm3 B 16 melanoma tumor by AC magnetic field led to tumor regression in female mice up to 40 %, and an increase of life span up to 300 % was achieved.