bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Hydrothermally Synthesized Greigite Magnetic Properties
Authors: Krivenkov Maxim , Gendler Tatiana , Novakova Alla
Published: July 2015

Greigite (Fe3S4) is an iron sulfide with inverse spinel structure, same as the structure of magnetite. Half-metallic properties in combination with ferrimagnetic nature of greigite puts this mineral in a fairly narrow group of materials that are potentially suitable for spintronics [1]. In this paper, we have conducted a comparative study of magnetic properties of two crystalline greigite samples obtained by hydrothermal synthesis with different parameters.Conducted Mossbauer spectroscopy study has shown that there are two magnetically non-equivalent B-site iron positions. The interpretation of this result was given using a model for magnetite from [2]. Unusual temperature dependencies of effective magnetic fields for A-and B-site iron atoms were obtained. It was found that coercive magnetic parameters as well as greigite stability depend on the synthesis procedure. Stepwise thermomagnetic analysis in saturating field allowed us to obtain the synthesized greigite critical temperatures of structural stability (T ~ 240oC), after which the sequential process of greigite transformation to pyrite, metastable maghemite (or magnetite) and finally to hematite begins. All of the found greigite peculiarities not only expand the knowledge about this complicated ferrimagnetic phase but can be used as guidance for optimal synthesis conditions.
Temperature Dependence of Electronic and Magnetic Properties of (DOEO)4[HgBr4]·TCE Single Crystals
Authors: Chernenkaya Alisa , Koplak Oksana , Medjanik Katerina , Kotov Aleksandr , Morgunov Roman , Yagubskii Eduard , Elmers Hans Joachim , Schönhense Gerd
Published: July 2015

The temperature dependence of electronic and magnetic properties of the organic charge-transfer salt (DOEO)4[HgBr4]·TCE was investigated using magnetometry. The magnetic susceptibility shows a maximum at 40 K followed by an onset of a pronounced increase at 70 K and a constant behavior above 120 K. Implications on the charge carrier density are discussed. Combining the magnetometry with resistivity and ESR measurements we propose a sequence of insulating, metallic and semiconducting behavior with increasing temperature. Our results indicate that (DOEO)4[HgBr4]·TCE is close to the boundary between an insulating and conducting ground state.
First Principles Investigations of Structural and Magnetic Properties of Fe-Ni-Mn-Al Heusler Alloys
Authors: Buchelnikov Vasiliy D. , Klyuchnikova Marina A. , Zagrebin Mikhail A. , Sokolovskiy Vladimir V.
Published: July 2015

In this work the magnetic and structural properties of quaternary Fe-Ni-Mn-Al Heusler alloys are studied. We use first principles calculations to investigate crystal lattice relaxation of alloys and their coupling to the magnetic order, with a particular focus on the tetragonal distortions characterized by the c/a ratio. It follows from our calculations that Fe-Ni-Mn-Al alloys have very interesting magnetic properties and can be good candidates as multifunctional magnetic materials.
Low-Temperature Spin Fluctuations beyond Spin Waves
Authors: Melnikov N.B. , Reser B.I.
Published: July 2015

A simple low-temperature dynamic spin-fluctuation theory of ferromagnetic metals is developed. The theory is based on the functional integral formalism for the multiband Hubbard Hamiltonian and takes into account both single-site and nonlocal spin fluctuations. We show that our approach correctly reproduces the T3/2 law at low temperatures. The calculated results of magnetic properties for Fe and Fe0.65Ni0.35 Invar demonstrate that the approach works on a much wider temperature interval than the spin-wave approximation.
Magneto-Optical Study of Martensitic Transition in Ni45Mn36.7In13.3Co5 (at. %) Single Crystals
Authors: Gan’shina Elena , Novikov Andrey , Chernenko Volodymyr , Barandiaran J. , Cesari Eduard , Rodionov Igor , Titov Ivan , Prudnikov Valeriy , Granovsky A.
Published: July 2015

Transverse Kerr effect (TKE) was used to study magneto-optical (MO) properties of Ni45Mn36.7In13.3Co5 (at.%) single crystals. A single crystalline ingot of such composition was grown by the Czochralski method. One series of samples was quenched into cold water (WQ) and the other series after quenching was heated at 770 K for 20 min and slowly cooled to assure a complete atomic order (SC). Accordingly to differential scanning calorimetry (DSC), magnetic and magneto-optical (MO) measurements, WQ samples exhibit well-defined martensitic transition (MT), but the SC samples do not show MT. It is found that TKE for WQ samples shows the following features (i) MO signal is well pronounced far below the martensitic transition in spite of a weak magnetization of martensitic phase; (ii) the characteristic temperatures of martensitic transition differ from those for the bulk and depend on annealing conditions; (iii) MO spectra profile do not change significantly during the martensitic transition and is similar but not identical with that for Ni50Mn35In15 thin films and Ni43.7Mn43.6In12.7 ribbons measured before; (iv) MO signal is anisotropic.
Untypical Temperature Dependence of the Magnetocaloric Effect in the Dy(Co1-xFex)2 (x = 0.10; 0.15) Compounds
Authors: Anikin Maksim S. , Tarasov Evgeniy N. , Kudrevatykh Nikolay V. , Zinin Aleksander V.
Published: July 2015

A study of crystalline structure, magnetic and magnetocaloric properties of Dy(Co1-хFeх)2 (х = 0.10, 0.15) intermetallic compounds was undertaken. Phase composition was controlled by X-ray diffraction analysis. Magnetic properties were measured with a help of SQUID magnetometer in magnetic fields up to 7 Т in the temperature range from 4.2 K to 400 K. Magnetic transition temperatures from paramagnetic to magnetically ordered state were inferred as 288 K and 350 K, respectively. It is shown that at an increase of iron concentration and/or magnetic field intensity, a considerable maximum broadenings on a temperature dependence of magnetic entropy change is observed. The calculated value of the relative cooling power (RCP) of Dy(Co0.90Fe0.10)2, in a magnetic field of 1.7 T is equal to 152 J/kg that is close to that for Gd metal with RCP = 181 J/kg at μ0Н = 2 T.
Magnetic Properties of Rapidly Quenched Ribbons of Soft Magnetic Iron-Based Alloys after Annealing in Air and in Vacuum
Authors: Skulkina Nadezhda A. , Ivanov Oleg A. , Stepanova Elena A. , Pavlova Irina O.
Published: July 2015

The physical reasons of influence of heat treatment in vacuum and air on magnetic properties of ribbon’s of amorphous soft magnetic iron-based alloys were investigated. It is shown that the heat treatment in the air contributes to retrieve the status of a material with lower specific magnetic losses. The reason for this is the formation during annealing of increased concentration along the axis of the ribbon of embedded in the surface atoms of hydrogen and oxygen. In this direction induced pseudo-uniaxial tensile stress, contributing to the reduction of the period of the domain structure and the speed of domain walls motion in the process of magnetization reversal.
Manipulation of Magnetic Properties and Domain Wall Dynamics of Amorphous Ferromagnetic Co68.7Fe4Ni1B13Si11Mo2.3 Microwire by Changing of Annealing Temperature
Authors: Chichay Kseniay , Rodionova Valeria , Ipatov Mihail , Zhukova Valentina , Zhukov Arkadi
Published: July 2015

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About the Importance of Choosing Bidisperse Approximation for Describing Real-World Polydisperse Ferrofluids
Authors: Novak Ekaterina
Published: July 2015

Two different bidisperse approximations of one gamma-distribution were examined in the present manuscript. The bidisperse system was chosen as the first step to allow for polydispersity when studying thermodynamics and microstructure of magnetic fluids. The author used the first-order modified mean-field model for investigating magnetization curves for these approximations and showed that curves are almost identical. Also analyzed was the influence of choosing variant of constructed bidisperse model on the structure factors, which were constructed using the mathematical model, developed in the paper by Novak et al. [J.Chem.Phys. 139 (2013) 224905].
Anomalous Temperature and Field Behaviors of Magnetization in Cubic Lattice Frustrated Ferromagnets
Authors: Ignatenko A.N. , Katanin Andrey A. , Irkhin Valentin Yu.
Published: July 2015

Thermodynamic properties of cubic Heisenberg ferromagnets with competing exchange interactions are considered near the frustration point where the coefficient D in the spin-wave spectrum Ek ~ Dk2vanishes. Within the Dyson-Maleev formalism it is found that at low temperatures thermal fluctuations stabilize ferromagnetism by increasing the value of D. For not too strong frustration this leads to an unusual "concave" shape of the temperature dependence of magnetization, which is in agreement with experimental data on the europium chalcogenides. Anomalous temperature behavior of magnetization is confirmed by Monte Carlo simulation. Strong field dependence of magnetization (paraprocess) at finite temperature is found near the frustration point.
Influence of Rotation on the Magnetization of Dilute Suspensions of Magnetic Particles
Authors: Tyatyushkin Alexander
Published: July 2015

The influence of rotation on the magnetization of a suspension of spherical magnetic particles in a uniform magnetic field is investigated theoretically with taking into account the inertial effects. A rotation of a single spherical non-Brownian particle with an embedded magnetic moment under action of a rotational flow of the ambient liquid in an applied uniform magnetic field is considered. The system of equations is obtained that determines the rotation of the particle and the instant orientation of its magnetic dipole moment with taking into account both the inertia of the particles and that of the dispersion liquid of the suspension. The magnetization vector of a suspension of non-Brownian spherical magnetic particles is found for the suspension rotating in a uniform constant magnetic field and for that rotating in a sufficiently weak uniform alternating magnetic field. The system of equations is obtained for the function of distribution over the orientations of the magnetic dipole moments for a suspension of Brownian spherical magnetic particles rotating in a uniform magnetic field. The solution to this system of equations is obtained for a suspension rotating in a sufficiently weak alternating magnetic field. With the use of this solution, the magnetization vector of the suspension is found.
Macroproperties of the Magnetic Systems with Anisotropic Microstructural Units
Authors: Pyanzina Elena
Published: July 2015

We present the theoretical study of the magnetic and thermodynamic properties for the systems with anisotropic magnetic units and results of computer simulations. We focus our attention on the theoretical description of the initial susceptibly and structure factor. An extensive comparison of our theoretical model to the results of molecular dynamics simulations for a wide range of system parameters demonstrated good quantitative and qualitative agreement. As a result, we can say that the macroscopic responses of the systems drastically change with the anisotropy of the microstructural units.
Thermodynamics of Bidisperse Ferrofluids in Zero External Magnetic Field: Theory and Simulations
Authors: Solovyova Anna Yu. , Elfimova Ekaterina A.
Published: July 2015

The thermodynamic properties of a ferrofluid modeled by a bidisperse system of dipolar hard spheres in the absence of external magnetic field are investigated using theory and simulations. The theory is based on the virial expansion of the Helmholtz free energy in terms of particle volume concentration. Comparison between the theoretical predictions and simulation data shows a great agreement of the results.
Magnetic Fluid Bridge between Coaxial Cylinders with a Line Conductor in Case of Wetting
Authors: Vinogradova Alexandra , Naletova Vera , Turkov Vladimir
Published: July 2015

We consider a heavy, incompressible, homogenous, isothermal magnetic fluid between two coaxial cylinders in case of wetting. There is a current-carrying straight wire on the axis of these cylinders. The magnetic fluid is immersed in a non-magnetic liquid with the same density (the case of hydroimponderability). We apply the Langevin law to describe a magnetic fluid magnetization. Using the general analytical solution for any axially symmetric shape of the magnetic fluid free surface in any axisymmetric magnetic field, we investigate the break-up and the rebuilding of the magnetic fluid bridge in case of wetting.
Heat Transfer in Boiling Magnetic Fluid in a Magnetic Field
Authors: Yanovskiy Aleksandr A. , Simonovsky Aleksandr Ya. , Kholopov Vladimir L. , Chuenkova Irina Yu.
Published: July 2015

In the present work we report the investigation of heat exchange processes at stationary boiling regime of magnetic fluid on a horizontal surface under magnetic field H ≤ 4.2 kA/m. In the presence of uniform magnetic field the specific thermal flow arriving to boiling magnetic fluid increases by 1.5 - 2 times. We offer the mechanism of magnetic field influence on heat exchange intensity in boiling magnetic fluid. The volume, shape and contact area of steam bubbles in horizontal heating surface in magnetic field is studied. The equation, connecting a specific thermal flow, magnetic field gradient and magnetic fluid magnetization in bubble boiling regime of magnetic fluid is written.
Adsorption and Magnetic Properties of Ultrathin Fe and Ni Alloy Films with an Inhomogeneous Magnetization Distribution
Authors: Pilipenko Dmitrii V. , Mamonova M.V. , Prudnikov Vladimir V.
Published: July 2015

Theoretical description of ultrathin ferromagnetic Fe and Ni alloy film adsorption on a nonmagnetic metal substrate is considered by the spin-density functional method. The conditions for the formation of ultrathin ferromagnetic films stable with respect to island adsorption with a change in the coverage parameter θ and Fe content concentration x are revealed. The equilibrium vacuum gap Dmin and the equilibrium film thickness hmin are determined from the minimum of the total interfacial energy. The energy and magnetic characteristics of FexNi1-x films on close-packed W and Cu surfaces are calculated in dependence on concentration x for different temperatures.
Magnetoelectric Effect in Ferrite-Piezoelectric Dual-Phase Structure
Authors: Petrov Roman V. , Tatarenko Alexander S. , Petrov Vladimir M. , Bichurin Mirza I.
Published: July 2015

This manuscript is devoted to the magnetoelectric coupling in a dimensionally graded magnetostrictive-piezoelectric structure in the electromechanical resonance region. Theoretical frequency dependence of ME voltage coefficient is obtained. Theoretical estimates for the layered structure of lead zirconate-titanate and single-crystal Zn0,3Ni0,7Fe2O4 are in satisfactory agreement with data. The obtained results are expected to facilitate observation of enhanced ME coupling at overlapping of electromechanical and magnetic resonance due to energy transfer between spin waves and phonons.
Crystal and Magnetic State of Multiferroic Composites (x)MFe2O4 + (1-x)BaTiO3, M = Ni, Co
Authors: Nosov Alexander P. , Semkin Mikhail A. , Teplykh A.E. , Bogdanov S.G. , Urusova Natali V. , Skryabin Yu.N. , Pirogov Alexander N. , Vasiliev Victor G. , Vladimirova Elena V. , Karpova Tatyana S.
Published: July 2015

Multiferroic composites of (x)NiFe2O4 + (1-x)BaTiO3 with x = 0.2, 0.3 and 0.4 and (x)CoFe2O4 + (1-x)BaTiO3 with x = 0.2, and 0.4 have been synthesized by mixing NiFe2O4 (CoFe2O4) spinel and BaTiO3 piezoelectric. Distribution of Ni (Co) ions on 8a and 16d positions of spinel lattice (space group Fd-3m) is determined by neutron powder diffraction. Wave vector of magnetic structure of the spinel is k = 0. The dielectric permittivity of the composites was measured for the frequency range 102 – 105 Hz. At low frequencies the dielectric permittivity decreased from ~940 for x = 0.2 to ~360 for 0.4.
Effect of Corona Treatment on Magnetic Properties of Nanoscaled Multiferroic Films BiFeO3, (BiLa)FeO3 and (BiNd)FeO3
Authors: Kostishyn V.G. , Krupa Nikolay N. , Panina Larissa V. , Nevdacha Vitaliy V. , Chitanov D.N. , Truhan V.M. , Yudanov N.A.
Published: July 2015

Multiferroic films of BiFeO3, (BiLa)FeO3and (BiNd)FeO3with various concentration of ions of Bi, La and Nd in dodecahedral sublattice utilising were fabricated on monocrystalline substrates of (001) SrTiO3, (100) MgO and (100) Al2O3by a number of technological methods: rf sputtering, vacuum laser ablation and metal-organic chemical vapor deposition (MOCVD). The film thickness varied in the range of 30-300 nm. The magnetic and magnetoelectric properties of the obtained films were investigated. The saturation magnetization of BiFeO3was about 9 emu/cm3which is typical of strained films of this composition. Doping BiFeO3films by rear earth ions La (Nd) increases both the magnetisation saturation and Neel temperature, as well as magnetoelectric effects, which is explained by increase in magnetic crystal anisotropy and suppression of spatially modulated magnetic structure. It was demonstrated that the corona discharge treatment resulted in a substantial growth of the magnetisation saturation up to 35% whereas the changes in the Neel temperature were not noticible. This is explained by the induced electret state and giant magnetoelectric effect.
Hall Effect Induced by Spin-Wave Excitation in Metal/Ferromagnetic Insulator Bilayer
Authors: Vedyayev Anatoly , Zhuravlev Mikhail , Titova Maria , Gusakova Daria , Ryzhanova N.
Published: July 2015

We investigate Anomalous Hall effect in nonmagnetic metal/ferromagnetic insulator bilayer with rotating magnetization of the magnetic insulator. Spin-orbit interaction of Rashba type takes place near metal/insulator interface. Magnetization of the ferromagnetic insulator rotates with some frequency w by microwave radiation under ferromagnetic resonance condition. This rotation together with spin-orbit interaction in non-magnetic metal layer induced Hall current along the interface. The Hall current appears under zero bias in the system. The dependence of Hall current on the exchange splitting, the magnetization rotation frequency and the barrier height is calculated. We analyze various contributions in Hall current and discuss the limit of small frequencies.
Anomalous Hall Effect in (Co41Fe39B20)x(Al–O)100-x Nanocomposites: Temperature Dependence
Authors: Mikhailovsky Yuriy O. , Prudnikov Valery N. , Chernoglazov Konstantin Yu. , Rylkov Vladimir V. , Nikolaev Sergey N. , Sitnikov Alexander V. , Kalinin Yuriy E. , Bartov Doron , Gerber Alexander , Granovsky A.B.
Published: July 2015

We present our last results on anomalous Hall effect (AHE) in (Co41Fe39B20)x(Al–O)100-x nanocomposites focusing on the possible correlation between temperature dependence of AHE and resistivity. It is shown that the temperature dependence of conductivity G=1/Rxx, where Rxx is resistivity, for compositions with x=49-56% at 10K<T<Tk follows the relation, where the parameters A, , Tk depend on x. For x=47% this relation changes to the exponential law “1/2” Rxx ∝ exp (Т0/T)1/2. The correlation between AHE resistivity RH (T) and resistivity Rxx (T) can be described as RH ∝ (Rxx)m , where m increases from 0.38 to 0.58 with an increase of x from 49 to 56 %.
Simultaneous Localization of Electrons in Different Δ-Valleys in Ge/Si Quantum Dot Structures
Authors: Zinovieva Aigul , Stepina Natalia , Dvurechenskii Anatoly , Kulik Leonid , Mussler Gregor , Moers Juergen , Grützmacher Detlev
Published: July 2015

In the present work the possibility of simultaneous localization of two electrons in Δ100 and Δ001 valleys in ordered structures with Ge/Si quantum dots (QD) was verified experimentally by electron spin resonance (ESR) method. ESR spectra obtained for the ordered ten-layered QD structure in the dark shows the signal corresponding to electron localization in Si at the Ge QD base edges, in Δ100, Δ010 valleys (gzz=1.9985, gin-plane=1.999). Light illumination causes the appearance of a new ESR line (gzz=1.999) attributed to the electrons in Δ001 valley localized at the QD apexes. Observed effect is explained by enhancement of electron confienment near QD apex by Coloumb attraction to the photogenerated hole trapped in Ge QD.
Magnetic and Magnetoresistance Properties of (Co/Ge)n Films
Authors: Patrin Gennady , Turpanov Igor , Maruschenko Ekaterina , Patrin Konstantin , Kobyakov Alexander , Maltsev Vadim , Yushkov Vasily
Published: July 2015

The magnetic and electrical properties of (Co/Ge)nfilms are experimentally studied. It is established that at the Co/Ge interfacean intermediate magnetic layer forms. Twophases of cobalt, one is a face-centered cubic phase and the other ispresumably a Co–Ge alloy with a weakly ferromagnetic order, have been found toexist. A “dead” layer no more than 2 nm in thickness is formed at the interface.This layer affects the magnetic behavior andmagnetoresistive effect in the investigated structures.
Enhancement of Exchange Bias in NiFe/IrM, IrMn/NiFe and NiFe/IrMn/NiFe Structures with Different Thickness of Antiferromagnetic Layer
Authors: Rodionova Valeria , Dzhun Irina , Chichay Kseniay , Shevyrtalov Sergey , Chechenin Nikolai
Published: July 2015

The Influence of the ferromagnetic (FM) and antiferromagnetic (AFM) layers position and of the thickness of antiferromagnetic (AFM) layer on magnetic properties of FM/AFM bilayer structures was studied. Angular dependences of the coercive force and exchange bias field were analyzed for NiFe/IrMn bilayer structures with different thickness of AFM layer. In some samples we observed the maximum values of the exchange bias field in the directions different from the magnetic easy axis.
Bias Current Effect on Second Harmonic in Asymmetric Magnetoimpedance Response in Amorphous Microwires
Authors: Buznikov N.A. , Antonov A.S. , Granovsky A.B.
Published: July 2015

The influence of bias current on the second harmonic in the nonlinear magnetoimpedance in an amorphous microwire with a helical anisotropy is studied theoretically. The voltage response of the microwire is found in the framework of a rotational model. It is shown that the application of the bias current leads to the asymmetry in the field dependence of second harmonic. The second harmonic amplitude is analyzed as a function of the external field, current amplitude and the value of the bias current. The conditions of maximum field sensitivity of the second harmonic are found.
Anisotropic Magnetoresistance and Weak Localization in Granular System Ni-MgO
Authors: Grebennikov Anton , Stognei Oleg
Published: July 2015

Magnetoresistive effect and electrotransport properties of Niх(MgO)100-х (x: 21-48 at.%) granular composites have been investigated. It is found that prepercolated composites (x < 24 at.%) do not exhibit magnetoresistive properties. After percolation threshold (x: 27-29 at.%) the composites exhibit isotropic negative magnetoresistance (-0,2 %) which has not tunneling nature. Also weak localization is realized in these samples at temperatures below 100 K. At high metal concentration (32 at.% < x) the composites exhibit anisotropic magnetoresistance.
Unidirectional Anisotropy in Nanostructures with Antiferromagnetic NiFeMn Layer
Authors: Blinov Iliya V. , Krinitsina Tatiana P. , Milyaev Mikhail A. , Popov Vladimir V. , Ustinov Vladimir V.
Published: July 2015

Magnetic properties of nanostructures including an antiferromagnetic (NiFe)1-хMnx alloy have been studied for various modes of this AFM layer preparation. The possibility for application of the AFM (NiFe)1-хMnx alloy as a material of the pinning layer in spin valves is discussed.
Spectral Ellipsometry of Cobalt-Ions Implanted Silicon Surface
Authors: Bazarov Valerii V. , Valeev V.F. , Nuzhdin V.I. , Osin Yu.N. , Gumarov G.G. , Stepanov Andrey L.
Published: July 2015

Monocrystalline silicon wafers implanted by cobalt ions with energy of 40 keV at a fluence range from 6.6×1012 to 2.5×1017 Co+-ion/cm2 were investigated by optical spectroscopic ellipsometry. By comparison of experimental data with modeling it is shown that the ellipsometric measurements are accurate and reliable method for monitoring of a low-dose ion implantation process.
New Iron(II) Complexes [Fe(HC(Pz)3)2]A2 with Spin-Crossover
Authors: Shakirova Оlga G. , Kuratieva Natalia V. , Korotaev Evgeny V. , Lavrenova Ludmila G.
Published: July 2015

Three new coordination compounds of iron (II), [Fe (HC(Pz)3)2](C8H5O4)2.C8H6O4(I), [Fe (HC(Pz)3)2](C10H7SO3)2.2H2O (II) and Fe (HC(Pz)3)2](C12H25SO4)2(III), where HC(Pz)3is the tridentate chelatortris(pyrazol-1-yl) methane, have been synthesized and investigated by X-ray structure analysis, electronic and IR spectroscopy, static magnetic susceptibility method. The magnetochemical study of complexes I–III in the interval from 300 to 500 K showed that they possessed the high-temperature spin crossover1A1↔5T2accompanied by thermochromism (the pink ↔ white color change).
Magnetic Properties of Nanocomposites Metal-Carbon
Authors: Aleshnikov Alexander , Al-Azzawi Haider S. Mohammed , Kalinin Y. , Sitnikov Alexander , Tarasova Oksana
Published: July 2015

The films of heterogeneous systems based on ferromagnetic alloy and С were obtained by ion-beam sputtering. The concentration dependence of the resistance of composites was measured before and after heat treatment. The research of magnetostatic and magnetodynamic properties of heterogeneous metal-carbon showed that compounds (Co)Х(C)100-Х (Co40Fe40B20)Х(С)100-Х (Co45Fe45Zr10)Х(C)100-Х after the percolation threshold have good soft magnetic properties.
Peierls “Washboard” Controls Dynamics of the Domain Walls in Molecular Ferrimagnets
Authors: Kirman Marina , Talantsev Artem , Morgunov Roman
Published: July 2015

The magnetization dynamics of metal-organic crystals has been studied in low frequency AC magnetic field. Four modes of domain wall motion (Debye relaxation, creep, slide and over - barrier motion (switching)) were distinguished in [MnII(H(R/S)-pn)(H2O)] [MnIII(CN)6]⋅2H2O crystals. Debye relaxation and creep of the domain walls are sensitive to Peierls relief configuration controlled by crystal lattice chirality. Structural defects and periodical Peierls potential compete in the damping of the domain walls. Driving factor of this competition is ratio of the domain wall width to the crystal lattice parameter.
FMR and Magnetic Properties of (CoFeB)m(SiO2)100-m Nanocomposite
Authors: Vyzulin Sergey , Syr'ev Nikolay , Shlapakov Mikhail
Published: July 2015

Multilayer nanogranular film structures (CoFeB)m(SiO2)100-mhave been investigated by ferromagnetic resonance (FMR). It is shown experimentally that for these films which magnetic phase content is below percolation threshold the variation of FMR fields is not related to the thickness of magnetic layers but can be explained by variation of the shape (elongation) of spheroidal magnetic granules. The observed results are explained within standard phenomenological FMR theory.
Fourfold Magnetic Anisotropy of CoPd Alloy, Obtained by Solid State Reactions in Epitaxal Pd/hcp-Сo and Pd/fcc-Co Bilayers
Authors: Myagkov V.G. , Bykova L.E. , Zhigalov V.S. , Tambasov I.A. , Bondarenko G.N. , Matsynin A.A.
Published: July 2015

The solid-state reaction between epitaxial hcp-Co (110) and fcc-Co (001) thin films and Pd layers was investigated at annealing temperatures between 250 and 650 °C using X-ray diffraction and magnetic measurements. No significant intermixing of the layers occurs at annealing temperatures below 400 °C. For the atomic composition 1Co:1Pd after annealing at 450 °C the disordered solid solution fcc-CoxPd1-x is formed on the Pd/hcp-Co (110) and Pd/fcc-Co (001) interfaces. Epitaxial relationships CoPd (110)〈-111〉 || MgO(001)〈100〉 and CoPd (001)〈100〉 || MgO(001)〈100〉 between the nucleated disordered phase CoPd and the substrate MgO(001) were determined for Pd/hcp-Co (110) and Pd/fcc-Co (001) bilayers, respectively. The first magnetocrystalline anisotropy constant of the disordered CoPd phase ​​K1CoPd = - (1.8 ± 0.4)·104 J/m3 for the (110) and (001) orientations was obtained.
Magnetic and Magnetotransport Properties of Fe-NbO System
Authors: Grebennikov Anton , Stognei Oleg , Semenenko Konstantin , Tregubova Tatijana
Published: July 2015

Magnetoresistive effect and electrotransport properties of Fe-NbO (13 ≤ Fe, at.% ≤ 80) thin films annealed at 600 °C has been investigated. It has been established that the samples structure contains three main phases Fe, NbO2, Fe2.9O4. Maximum of magnetoresistance in the samples does not exceed 0.3%, a coercive force is ranging from 150 to 370 Oe, depending on the Fe concentration. It is assumed that the films have a granular structure. Magnetoresistance and coercive force values, as well as the correlation between the magnetoresistance and the magnetization of the Fe-NbO samples are uncharacteristic for granular systems. It is assumed that uncharacteristic properties are due to the significant influence of ferrite Fe2.9O4 on the magnetic properties and electrotransport of the Fe-NbO films.
Magnetic Anisotropy of Co-Nanostructures Embedded in Matrices with Different Pores Size and Morphology
Authors: Denisova Elena , Chekanova Lidia , Iskhakov Rauf , Komogortsev Sergey , Nemtsev Ivan , Velikanov Dmitry , Mel’nikova Svetlana
Published: July 2015

Composite materials with Co (P) particles embedded into pores of silica and track etched polycarbonate membranes were fabricated by an electroless reduction. The magnetic and structural properties of the composite materials are characterized by scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometer. The macroscopic and local magnetic anisotropy of the Co (P) particles electroless deposited in the pores of the polycarbonate membrane and silica is studied. The composite materials with linear pores exhibit uniaxial magnetic anisotropy. The easy axis lies along the Co (P) rods, the shape anisotropy dominates over the intrinsic crystalline anisotropy. Information on local anisotropy field and the grain size was obtained from investigation of approach to saturation magnetization law. The local anisotropy field for all the samples depends on P content. For Co (P) rods the local anisotropy value is also determined by nominal pore sizes. It was found that the investigated Co (P) rods is nanocrystalline. The effects of different pores morphology on the FMR-spectra characteristics are studied.
Magnetic Clusters in Natural Ferro-Chromian Spinels
Authors: Sherendo Tatyana , Mitrofanov Valentin , Vdovin Aleksey , Martyshko Petr , Alexeev Aleksey , Zamyatin Dmitry , Vazhenin Vladimir , Pamyatnykh Lidia
Published: July 2015

The results of investigations of natural iron-chromium spinels of variable composition Fe2+(Cr2-xFex3+)O4 of the chromite-bearing Klyuchevskoi massif (Middle Urals), which are the main carriers of the magnetization of rocks are presented. Substantial changes in the composition and in magnetic structure of accessory chrome-spinels scattered in the host rock are established, unlike the almost unaltered ore-forming chrome-spinels, under the influence of secondary geological processes. To establish the connection between the chrome-spinel changes at the microlevel and features of the geomagnetic field anomalies created by this carrier of magnetization of rocks, it is carried out a complex of investigations of Fe-Cr-spinels (thermomagnetic analysis over the temperature range (4÷1000) K; magnetic resonance (MR) spectroscopy and magnetic force microscopy (MFM) in addition to magnetomineralogical studies). As a result, in the relict areas of grains of the accessory chrome-spinels were first discovered the magnetic clusters (superparamagnetic phases) in the form of single or groups of 2 – 3 magnetic dipoles of tens nanometers in size, or in the form of chain-like structures of magnetic dipoles/single domains.
Structure and Magnetic Properties of FeNi/Ti Multilayered Films Grown by Magnetron Sputtering
Authors: Svalov Andrey V. , Vas’kovskiy Vladimir O. , Larrañaga A. , Kurlyandskaya Galina V.
Published: July 2015

Structure and magnetic properties of FeNi/Ti multilayers prepared by magnetron sputtering were studied. The dependences of the spontaneous magnetization and hysteresis features of the films on the thickness of the magnetic layers were established. It was shown that these properties were to a large extent determined by interlayer interfaces, in which the effective magnetization decreases. The possible reason for the interface peculiarities was the interlayer mixing. The presence of (FeNi)Ti phase which was formed by the interdiffusion of FeNi and Ti layers was confirmed by X-ray diffraction measurements.
Optical Second Harmonic Generation in Nanostructures with Inhomogeneous Magnetization
Authors: Kolmychek Irina A. , Krutyanskiy Victor L. , Murzina Tatyana , Karashtin Evgeniy A. , Sapozhnikov Maxim V. , Fraerman Andrey A.
Published: July 2015

The effects of inhomogeneous magnetization on optical second harmonic generation from magnetic nanostructures are studied. Cobalt triangular-shaped nanoparticles with vortex magnetization and magnetic trilayers that support the ferromagnetic phase formation are considered. We show that magnetic field dependencies of the SHG intensity for both types of structures reveal a number of distinct peculiarities associated with additional SHG mechanisms attributed to inhomogeneous magnetic state of the nanostructures.
Magnetic and Magneto-Optical Properties of Magnetoplasmonic Crystals
Authors: Belyaev Viktor , Grunin Andrey , Fedyanin Andrey , Rodionova Valeria
Published: July 2015

Nano systems with combined magnetic and plasmonic functionalities have become an active topic of research in recent years. By an adequate internal architecture of the constituting components, the magneto-optical activity of these systems can be greatly intensified due to the electromagnetic field enhancement associated with the plasmon resonance. One of such approaches is a creating of magnetoplasmonic crystals (MPlCs) based on the noble and ferromagnetic metals. This work represents results of the investigation of the magneto-optical (MO) properties of the magnetoplasmonic structure, and parameters of the magnetic field sensor based on such structures. Possibility of creation of the magnetic field sensor with different properties is represented.
Micromagnetic Calculation of Neel Domain Wall Structure
Authors: Semenov Vladimir S.
Published: July 2015

The numerical method of Brown and La Bonte [1] is used to calculate both the total equilibrium energy and the magnetization distribution of one-dimensional Neel domain wall (DW). The continuous magnetization distribution of Neel DW is replaced by a discrete distribution for which the magnetostatic energy was calculated precisely using high-speed computer program.
The Suppression of Demagnetizing Field Heterogeneity in Ferromagnetic Powders
Authors: Yaroslavtsev Roman , Komogortsev Sergey , Chekanova Lydia , Kuzovnikova Ludmila , Denisova Elena , Li Oksana , Velikanov Dmitry , Iskhakov Rauf
Published: July 2015

The two ways of reducing the dispersion of the demagnetizing fields in magnetic powders of cobalt alloys have been tested: the isolation of magnetic particles in nonmagnetic matrix and compaction of the powders. The ferromagnetic resonance (FMR) and the hysteresis loops of the pretreated magnetic powders were investigated. The FMR linewidth is significantly narrowed both with increasing of the nonmagnetic fraction in the samples prepared by the first way and with increasing of relative density of the compacts. The limit case of FMR linewidth in continuous magnetic film there is no dispersion of the demagnetizing fields is in good agreement with discussed data. The hysteresis loops of powder with the particles coated by the non-magnetic phase became narrow and easy saturated with increasing of nonmagnetic phase fraction.
Magnetic and Magnetoresonance Studies of Composite Multilayer Films with Different Kinds of Interlayers
Authors: Shipkova Irina , Chekrygina Juliya , Devizenko Aleksandr , Lebedeva Evgeniya , Syr'ev Nikolay , Vyzulin Sergey
Published: July 2015

Static magnetic properties, ferromagnetic resonance (FMR) and glancing angle X-ray diffraction spectra (GAXRD) of (CoFeB)/(nonmagnetic interlayer) nanosystems have been studied for three kinds of interlayers: dielectric (SiO2) and semiconductors (Si and SiC). Matter of discussion is the role of the interlayer material in forming of inner structure of magnetic layers and magnetization curve shape.
Spin Filtering on the MnSb Cluster Interface in GaSbMn Thin Films
Authors: Koplak Oksana , Polyakov Alexey , Davydov Alexander , Morgunov Roman , Talantsev Artem , Kochura Alexey , Fedorchenko Irina , Novodvorskii Oleg , Parshina Lubov , Aronzon Boris , Lähderanta Erkki
Published: July 2015

Effect of charge carriers concentration on magnetic parameters of the ferromagnetic MnSb nanoclusters as well as opposite effect of cluster magnetization on spin polarization of holes and magnetoresistance were observed in GaSbMn thin films. Microwave magneto-resistance effect is evidence of the charge carriers spin filtering by ferromagnetic clusters.
Surface Modification of Thin Iron Films in Aromatic Solvents at Ambient Conditions
Authors: Chlenova Anna A. , Kurlyandskaya Galina V. , Safronov A.P. , Larrañaga Aitor , Fernandez Armas Sergio , Zalbidea Arechaga I. , Lepalovskij Vladimir N.
Published: July 2015

Recently we reported interesting phenomenon resulting in formation of irregular polycyclic structures on the surface of Fe or Ni nanoparticles immersed in toluene at ambient conditions. The objectives of the present work were to test the possibility of ambient deposition of carbon on the surface of Fe film, to study the kinetics of the deposition and to characterize the structure of the deposits. Periodic structural and magnetic measurements were performed on the dry samples just taken out of toluene. We observed that carboneous layers on the Fe surface are formed rather fast – they can be initially detected after about one week treatment.
A Simple Model for Investigation of the Pair Breaking Effect on the Parameters of HTS/FM Thin Films
Authors: Nurgaliev Timerfayaz , Uspenskaya Ludmila
Published: July 2015

A simple model was proposed for description of Cooper pair breaking effect (which is caused by transfer of spin-polarized carriers from the ferromagnetic (FM) manganite into the high temperature superconductor (HTS)) on the critical temperature and the microwave surface impedance of HTS/FM heterostructures. The model is based on the assumption on an exponential dependence of the Cooper pairs concentration (as well as number of the holes in CuO2 planes, responsible for the superconductivity) on the distance from HTS/FM interface. The model fits well the thickness dependence of HTS film parameters and is used for evaluation of the penetration depth of spin-polarized particles into HTS in the HTS/FM structures.
Surface Properties of Nanoscale Iron Garnet Films
Authors: Kosykh T.B. , Prosyakov A.S. , Pyatakov A.P. , Shaposhnikov Alexander N. , Prokopov Anatoly R. , Sharay Irene V.
Published: July 2015

Surface properties of nanoscale iron garnet films of different compositions prepared by reactive ion beam sputtering were examined by means of scanning probe microscopy. Atomic force microscope images of the film surfaces are represented for the films of different compositions and deposition times. The article presents the dependences of the roughness parameters on the film composition and thickness and on the energy of Ar+ ions by which the substrates were pre-treated. It was shown that the roughness parameters of the films' surface increase with the increase of Ar+ ions energy and the films' thickness.
Canted Spiral Magnetic Order in Layered Systems
Authors: Timirgazin Marat T. , Gilmutdinov Vitaly F. , Arzhnikov Anatoly K.
Published: July 2015

Formation of a canted spiral magnetic order is studied in the framework of a mean-field approximation of the Hubbard model. It is revealed that this magnetic state can be stabilized under certain conditions in layered systemswith a relatively small interplane electron hopping. Example of an experimentally observed magnetic structure ofLa$_{2-x}$Sr$_x$CuO$_4$ is considered. It is shown that the canting magnetic order can be described in terms of a simplenon-relativistic band magnetism.
Magnetization Processes Study in the Implanted Garnet Films Using the Second-Harmonic Generation Effect
Authors: Bonda Adam , Uba Stanislaw , Uba Luba
Published: July 2015

In the work, magnetization-induced second-harmonic generation (MSHG) effect has been appliedto investigate the magnetization distribution changes, induced by ion implantation into thethin surface layer of garnet film.The studies were performed on the (111)-orientedepitaxial garnet film (YSmLuCa)$_3$(FeGa)$_5$O$_{12}$ implanted with $1.5\times10^{16}$~cm$^{-2}$dose of H$_2^+$ ions at $60$~keV energy. The measurements of the MSHG effectwere performed as a function of amplitude of perpendicular external magnetic field. The observed complex field dependencesof the remagnetization processes for the implanted garnet film studied were described in theframe of a phenomenological model developed. The model of the MSHG effect allows to performdecomposition of measured dependences on separate contributions originating from magnetizationcomponents related to implanted and unimplanted film volumes.
Influence of Annealing on the Surface Topography and Magnetic Properties of Thin Films of the FINEMET-Type Alloy
Authors: Mikhalitsyna Evgeniya , Kataev Vasiliy , Geydt Pavel , Lepalovsky Vladimir , Lähderanta Erkki
Published: July 2015

Surface structure and magnetic properties of thin films of the FINEMET-type alloy modificated by Mo (FeCuNbSiBMo) were studied in the aim of establishing of their dependence on heat treatment conditions. The thicknesses of the films were varied from 10 to 800 nm. Dependence of the microstructure of the films surface on the annealing temperature was analyzed using scanning probe microscopy. Parameters of the topography features were estimated as a function of the films thickness and annealing temperature. Magnetic hysteresis loops were measured using vibrating sample magnetometer and discussed in the focus of surface and thickness influences.
Structural and Magnetic Properties of Annealed Vapor Deposited CoxCr1-x Thin Films
Authors: Kharmouche Ahmed
Published: July 2015

Abstract. We prepared, under vacuum and onto monocrystalline silicone and glass substrates, series of CoxCr1-x thin films, with x ranging from 0.80 to 0.88. The structural and magnetic properties of the as deposited films have been performed using Rutherford backscattering spectrometry (R.B.S.), X-ray diffraction (X.R.D.), Alternating Gradient Field Magnetometer (A.G.F.M.), and Brillouin Light Spectrometry (B.L.S.) techniques. Once the films being annealed under vacuum, for 1 h at 700°C, in a pre-heated furnace, their structural and magnetic properties have been performed, by these tools, as well. Significant results have been found. The as deposited films present only an HCP structure and show a preferred orientation. The annealed films present both HCP and FCC structures. The annealed films possess cell parameters greater than the bulk ones which infer that they are under a tensile stress. The cell parameters of the as deposited films are lower than the bulk ones which infer that they are under a compressive stress. Up to the annealing temperature the films are still ferromagnetic and some decrease of the magnetic moment is noticed. In addition, coercivity and squareness have been strongly improved in the annealed films comparatively to the as deposited films. Moreover, the stiffness constant, computed using Brillouin light scattering measurements and after adjustment of theoretical and experimental results, is found to be far lesser than pure Co one. These results and others will be presented and discussed.
Effect of Co Doping on the Galvanomagnetic Properties of ZnO Thin Films
Authors: Kytin Vladiimir G. , Reukova Olga V. , Melnik Dannil D. , Burova Lidiya I. , Kaul Andrey R. , Kulbachinskii V.A.
Published: July 2015

The influence of the Co doping on the properties of zinc oxide films was investigated. The films were grown by oxygen and water assisted metal organic chemical vapor deposition (MOCVD). The large positive magnetoresistance (PMR) was observed in Co doped films at low temperatures while the negative magnetoresistance was observed in undoped ZnO films deposited under the same conditions. The relative variation of resistivity was comparable in the films grow by oxygen and water assisted MOCVD although the resistivity and its temperature dependence were significantly different. The magnitude of PMR increases with an increase of the Co content and with the decrease of temperature.
Magnetic Properties of Amorphous Hydrogenated Carbon Thin Films Doped by Ni
Authors: Lukitsa Ivan G. , Nikolaychuk Galina A. , Moroz Oleg Y. , Smirnov Valeriy M.
Published: July 2015

Amorphous hydrogenated carbon thin films were deposited on Si and glassceramics substrates by reactive ion-plasma magnetron sputtering. Thin films were without (a-C:H) and with Ni nanoparticles (a-C:H:Ni). Measurement of absorption coefficient in 220-850 nm spectral range using spectrophotometer and following approximation applying of Tauc method shows that obtained a-C:H thin films material has near 3.6 eV optical band gap and confirmed that this material is amorphous semiconductor. Thin films with Ni nanoparticles have a high complex permittivity ε* and permeability μ* (ε′ ≈ 1000–10000, ε′′ ≈ 100–1500, μ′ ≈ 10–70, μ′′ ≈ 0.4-10). Some magnetic parameters of thin films were determined.
On the Superconductivity of Planar Carbon Compounds
Authors: Zaitsev Rogdai
Published: July 2015

The problem of the superconductivity of σ electrons in compounds with a honecomb structure has been analyzed. The equations of superconductivity and the phase diagram have been obtained under the assumption that the Hubbard energy is the largest energy parameter.
Magnetic Prehistory in the Heat Capacity of the Low-Temperature Superconductors
Authors: Podgornykh Sergey Mikhailovich
Published: July 2015

Effect of the magnetic prehistory on the temperature dependence of the heat capacity of the superconducting Pb, La, Sn. has been studied. As soon as the external magnetic field riches the valueHext=HCthe superconductivity is completely destroyed. The trapped flux was produced in the ring specimen after the magnetic field was turned off atT<TC. We observed a difference of the value of the heat capacity between zero field cooled (ZFC) and field cooled (FC) states in zero magnetic field for the ring specimen. It is found that the FC heat capacity is smaller than the heat capacity both in the normal and in superconducting states.