bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Preparation of Magnetic Nanowires
Authors: Kalska Szostko Beata , Brancewicz Ewa , Olszewski Wojciech , Szymański Krzysztof , Sidor Anna , Sveklo Josif , Mazalski Piotr
Published: September 2009

Electrochemistry is a method, which can be used for creation of nanomaterials. This method has big advantage such as no restriction for shape and size of the sample and do not need to involve expensive equipment for the sample preparation.
In the paper the preparation of Fe nanowires as well as Co and Ni are presented. The diameter and length of obtained nanowires can be tuned by properties of the template porous material and time of deposition, respectively. The quality of the nanowires depends also from deposition mode (AC - alternating current or DC - constant current) and pH of the solution.
The anodization conducted in oxalic acid allows us to obtain anodic alumina oxide (AAO) with the smallest pore diameter of about 40 nm. Usage of phosphoric acid results in largest pores with diameter around 120 nm. The deposited material inside the pores has diameter of the templates. The length can be as large as the thickness of the oxide and reach up to around 1 μm. The wires shows magnetization direction along main axis. The morphology of wires were studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The magnetic characterization of the structures was done by magnetic force microscopy (MFM) and Mössbauer spectroscopy.
Electrically-Controlled Penicillin/Streptomycin Release from Nanostructured Polypyrrole Coated on Titanium for Orthopedic Implants
Authors: Sirivisoot Sirinrath , Pareta Rajesh A. , Webster Thomas J.
Published: September 2009

Implant infection leading to revision surgery can be avoided by incorporating controllable antibiotic release from titanium (Ti) implant surfaces. In this study, penicillin/streptomycin (P/S) and dexamethasone (Dex) were successfully immobilized via electropolymerization within polypyrrole membranes coated on the surface of Ti, which is widely used in orthopedic applications. In vitro results showed that greater numbers of osteoblasts adhered on these polymer-coated substrates than on currently-used unmodified Ti. X-ray photoelectron spectroscopy was used to monitor and compare the reaction effectiveness and the yield of electropolymerization. Polypyrrole membranes conjugated with P/S and Dex, and then coated with PLGA, all possessed nanometer scale roughness, as analyzed by atomic force microscopy. In summary, this study demonstrated that drugs incorporated within electroactive polypyrrole membranes, whose release was controlled by applying voltages, supported osteoblast adhesion and could potentially fight bacterial infection.
Hybrid Nanocomposite Coatings for Application in Construction Materials: Tribological Study
Authors: Silvestre Celia , López-Tendero M.J. , Cruz-Yusta Manuel , Baeza Noelia , Guillem Celia , San Juan Stephanie , Lloris J. Manolo , Tamayo Eduardo
Published: September 2009

The Nanocomposite group of AIDICO and the Nanomaterials Group of University of Valencia collaborate in the research of new organic-inorganic hybrid materials with application in construction products. Tribological properties and good thermal stability are some of the required specifications for such applications. Some hybrid coatings based on simultaneous formation of epoxy and silica networks are introduced in this work. Elastic modulus and hardness obtained from TDMA analyses and indentation techniques, together with thermal stability by TGA, are the main properties analysed in order to fulfil the requirements for construction coating applications. New routes for obtaining these coatings based on sol-gel have been explored.
Application of Polymer Swelling by scCO2 to the Synthesis of Polymer/Metal Nanocomposites
Authors: Vitoux Pauline , Majimel Mélanie , Tassaing Thierry , Letourneau Jean Jacques , Cansell François , Aymonier Cyril
Published: September 2009

Polymer swelling by scCO2 was mainly studied to understand many industrial processes, especially in the field of pharmacy for drug delivery (impregnation) and also polymer processing by CO2-assisted extrusion. We have studied here another application of polymer swelling by scCO2 for the synthesis of nanocomposites. The selected model system was the direct synthesis of copper nanoparticles in a poly(ethylene glycol) matrix (PEG). The study of the formation of nanostructures in polymer matrix is constituted of three main steps: i) thermodynamical behaviour of the polymer/CO2 system, ii) viscosity of the polymer/CO2 system and iii) nucleation and growth of copper nanoparticles.
First, the thermodynamical behaviour of the PEG/CO2 system was studied by in situ IR spectroscopy. This method gives accurate values of the polymer swelling by scCO2 but also of the CO2 sorption in the polymer. For example, at 40°C-15MPa, the swelling of PEG is equal to 35% for a CO2 solubility of 23 wt%. Secondly, we have developed an original falling ball viscometer for the determination of PEG viscosity as a function of CO2 density. A good knowledge of the polymer/CO2 system is finally used for the control of formation of copper nanoparticles. This formation was followed by in situ UV - visible spectroscopy and characterized by transmission electron microscopy.
A Solid-State Route for the Synthesis of Metal Nanocluster Composite Glasses
Authors: Cattaruzza Elti , Gonella Francesco , Ali Shahid , Bello Valentina , Cesca Tiziana
Published: September 2009

A field-assisted solid state ion exchange (FASSIE) approach is used to dope silicate glasses with mono- and/or multivalent ions, in which the diffusion of ions coming from a film deposited onto the glass surface is driven by an external electric field. Metal precipitation to form nanoparticles may take place during the ion exchange, depending on the process parameters, or it can be induced by irradiation with high power laser beams. Characterization of silicate glass samples doped with either gold or silver is performed by optical absorption and transmission electron microscopy.
Controlled Growth of ZnO Nanocrystals on the Surface of SiO2 Spheres
Authors: Yermolayeva Yuliya V. , Savin Yuriy N. , Tolmachev Alexander V.
Published: September 2009

The “islands” of ZnO nanocrystals on amorphous monodisperse 200 nm SiO2 spheres (core-shell particles) were obtained by simple one-step technique based on low-temperature crystallization from liquid phase. The influence of starting reagents types and concentration of zinc ions in the reaction mixture on the morphology of ZnO shells obtained was studied. Crystalline structure of ZnO nanocrystals obtained was proofed by the X-ray diffraction data. The average diameter of ZnO nanocrystals on SiO2 spheres is 10 nm according to X-ray diffraction (XRD) and transmission electron microscopy (TEM) data. It was shown that SiO2/ZnO particles obtained have high luminescence characteristics. Photoluminescence spectra of core-shell SiO2/ZnO particles show two emission peaks centred at 386 nm and 570 nm. Core-shell SiO2/ZnO particles obtained are perspective for active photonic crystals creation for UV-spectral region.
Development of Polymer Matrix Clay Nanocomposites for Industrial Applications Using High Throughput Methods
Authors: Jakubowicz Ignacy , Yarahmadi Nazdaneh
Published: September 2009

The development of polymer-layered silicate nanocomposites (PNCs) includes a long list of different possible components such as polymers, nano-additives, and co-additives, together with surface chemistry and various processing conditions. This involves the investigation of a large number of parameters that influence PNC performance. Consequently, fairly extensive research and development work is necessary, and this constitutes an obstacle in the commercialization of nanotechnology. This paper, which is based on experience from research and development for an industrial application, presents a procedure composed of high throughput (HT) screening methods for speeding up the development of PNCs.
SWCNT as Cure-Induced Stress Sensors in Epoxy Nanocomposites
Authors: De La Vega A. , de A. Prado L. A. S. , Kovacs J. Z. , Bauhofer W. , Schulte K.
Published: September 2009

Given their unique set of properties, carbon nanotubes are rapidly gaining importance as stress/damage sensors in addition to as mere reinforcing elements in polymer composites. In this work, single-walled carbon nanotubes (SWCNT) are used to monitor internal stresses developing during the curing process of thermoset materials. SWCNT-epoxy composites with high dispersion quality were obtained via calandering. In situ Raman spectroscopy was used to identify chemical and thermal induced stresses by following the changes in the G’-band versus time and temperature. Thermal shrinkage prompts a pronounced effect on the spectral shifts of the composite, pointing at its dominant role (over chemical shrinkage) on the development of the internal stress field. Above Tg, Raman shifts due to temperature increase are found to be negligible, confirming the existence of a stress releasing mechanism. Shift rate of the composites cooling from their processing temperatures depended on the combination of matrix/SWCNT type, pointing at the role of interfacial strength on the load transfer efficiency.
Effect of Charge Density on the Taylor Cone in Electrospinning
Authors: Stranger Jonathan , Staiger Mark P. , Tucker Nick , Kirwan Kerry
Published: September 2009

A detailed understanding of charge density and its origins during the electrospinning process is desirable for developing new electrospinnable polymer-solvent systems and ensuring mathematical models of the process are accurate. In this work, two different approaches were taken to alter the charge density in order to measure its effect on the Taylor cone, mass deposition rate and initial jet diameter. It was found that an increase in charge density results in a decrease in the mass deposition rate and initial jet diameter. A theory is proposed for this behaviour in that an increase in charge density leads to the tip of the Taylor cone forming a smaller radius of curvature resulting in the concentration of electric stresses at the tip. This leads to the electrostatic forces drawing the initial jet from a smaller effective area or “virtual orifice”.
A Study on the Effect of Nano-Magnesium Hydroxide on the Flammability of Epoxy Resins
Authors: Martins Marta , Pereira Celeste M.C.
Published: September 2009

In this work the effect of nano-magnesium hydroxide (nano-Mg(OH)2) on the flammability of epoxy composites is presented and compared with the traditional flame retardant used in just small amounts for epoxy resins, ammonium polyphosphate (APP). The fire reaction properties of epoxy composites were obtained by cone calorimeter tests. It was observed that the flammability of the unfilled resin is significantly changed with nano-Mg(OH)2 addition and reductions of 33, 22 and 23% in the epoxy composite heat release rate peak (PHRR) by incorporating 10%, 5 % and 1% of nano-Mg(OH)2, respectively, were achieved. Cone calorimeter analyses confirm the better behavior of APP composites compared with nano-Mg(OH)2 composites. SEM micrographs show some agglomerations on the distribution of nano-Mg(OH)2 in the epoxy matrix.
Flame Retardancy of Thermoset Polymers Based on Nanoparticles and Carbon Nanotubes
Authors: Pereira Celeste M.C.
Published: September 2009

An overview of the effects of different nanoscale materials on the flammability of two thermoset polymers is presented and discussed in this paper. Its goal is to bring together our recent experimental results obtained for different material systems of nanoclays, nano-magnesium hydroxide (nano-Mg(OH)2) and carbon nanotubes (CNT) in epoxy and unsaturated polyester resins; some of these results have already been published elsewhere. It is shown that these nanoparticles can be used to lower the heat release rate (HRR) of the polymers when exposed to a fire situation. On the other hand, in the majority of the cases this low flammability of polymer nanocomposites is only achieved in terms of HRR, but fails in terms of time-to-ignition or the extent of smoke released.
Plasma-Engineered Polymer Thin Films with Embedded Nanosilver for Prevention of Microbial Adhesion
Authors: Saulou Claire , Despax Bernard , Raynaud Patrice , Zanna Sandrine , Marcus Philippe , Mercier-Bonin Muriel
Published: September 2009

The present project is focused on the plasma-deposition of thin films (~150 nm) containing silver nanoparticles embedded in a polymeric matrix, to prevent microbial adhesion to stainless steel. The process originality relies on a dual strategy associating silver target sputtering and plasma polymerization in argon-hexamethyldisiloxane (HMDSO) plasma, using an asymmetrical RF discharge (13.56 MHz). The physico-chemical properties of the obtained films were investigated by transmission FTIR and XPS. To determine the anti-adhesive efficiency, detachment experiments were performed in a shear stress flow chamber with silver-containing and silver-free deposits. The maximal detachment efficiency was achieved with the polymeric matrix alone. Silver antimicrobial effect is assumed to be related to Ag+ ion progressive release from the embedded particles into the surrounding medium. This release was confirmed by ICP-MS measurements. Furthermore, film biocide activity was observed for silver-containing film.
Garnet Films for Thermo-Magnetic Recording and Nanotechnology Purposes
Authors: Berzhansky V.N. , Nedviga A.S. , Vishnevskii V.G. , Prokopov A.R.
Published: September 2009

High coercive garnet-ferrite films are being synthesized for thermo-magnetic recording, for example, by focused laser beams. These films can be characterized by a couple of parameters very suitable for recording reconfigurable magnetic atomic traps whose geometry is visible. On the other hand, slightly other films can be used for contact printing of high density and weak residual magnetization records in criminalistics. Both types are investigated experimentally in this work.
Hyperfine Interactions in Half-Doped and 2/3-Doped Charge-Ordering Manganites
Authors: Leskova Julia V. , Nikiforov Anatoliy E. , Gonchar Liudmila E. , Popov Sergey E. , Mozhegorov Alexey A.
Published: September 2009

The present work is devoted to the theoretical interpretation of nuclear magnetic resonance (NMR) spectra on nonmagnetic lanthanum ion in charge-ordered La0.5Ca0.5MnO3 and La0.33Ca0.67MnO3 compounds. It is shown that the anisotropic hyperfine interaction, which arises due to the polarization of lanthanum’s external p-shells, plays a crucial role in spectrum forming. Our model allows to explain experimental spectra. The work is partially supported by CRDF REC-005.
Oxygen Isotope Effect in Layered Manganites
Authors: Taldenkov A.N. , Babushkina N.A. , Inyushkin A.V. , Suryanarayanan R.
Published: September 2009

The oxygen isotope effect in ceramic bilayer manganite (La1 zPrz)1.2Sr1.8Mn216 18O7 (z = 0, 0.3, 0.4, 0.6) 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 40 kOe. Substantial decrease of ferromagnetic (FM) transition temperature TFM under oxygen isotope substitution 16O → 18O was found. This positive isotope effect amounts to more than 20 K. A number of additional transitions of ferromagnetic type were observed at T >170 K, which also depend on oxygen overall mass. The obtained results are compared with those observed in other manganites exhibiting the large isotope effect.
Observation of Domain Wall Resistance in La0.7Ca0.3MnO3 Films
Authors: Dyakonov K.V. , Popov V.V. , Dyakonov V.P. , Gierlowski P. , Lewandowski S.J. , Szymczak H.
Published: September 2009

We report the study of the magnetoresistance (MR) and resistivity as a function of temperature in epitaxial thin films of the La0.67Ca0.33MnO3 type (LCMO). The films deposited onto Y-cut of single-crystalline LiNbO3 (LNO) substrates by pulsed-laser deposition in an on-axis geometry. For comparison, the same manganite film deposited onto LaAlO3 (LAO) substrate is studied. The MR of LCMO/LNO film is found to be anisotropic and exhibits a hysteresis loops in low magnetic fields. When magnetic field is parallel to the film plane a number of jumps are observed in the MR below magnetic fields H~6 kOe. These jumps reflect the presence of pinning centers for domain walls. Evidently, a lattice deformation produced by a mismatch of lattice constants LCMO film and LNO, which lead to distortion of the film, is the origin of such strong pinning centers.
Oxygen Isotope Effect in Cr- and Ru-Doped Pr0.5Ca0.5MnO3 Manganites
Authors: Babushkina N.A. , Taldenkov A.N. , Inyushkin A.V. , Maignan Antoine , Khomskii D.I. , Kugel K.I.
Published: September 2009

The effect of 16О → 18О isotope substitution on the properties of Pr0.5Ca0.5MnO3 manganites doped by Cr and Ru is studied. In these compounds, chromium and ruthenium favor (i) the suppression of a charge-ordered state and (ii) the formation of a ferromagnetic metallic phase. The 16О → 18О isotope substitution leads to the growth of the charge-ordering transition temperature (TCO), and to the lowering of ferromagnetic transition temperature (TFM) accompanied by a decrease in the content of ferromagnetic phase. The difference in the behavior of the Cr- and Ru-substituted samples is analyzed.
Magneto-Hydrodynamic Interaction in an Inclined Layer of Ferrocolloid Heated from Below
Authors: Bozhko Aleksandra A. , Putin Gennady F. , Tynjälä Tero
Published: September 2009

The instability of convection patterns representing a combination of vertical Rayleigh rolls and horizontal rolls resulting from longitudinal horizontal magnetic field is investigated in an inclined layer of magnetic colloid by experiments and numerical simulations. Visualization of convection patterns is provided by a temperature-sensitive liquid crystal film. The rich spectrum of convection structures is observed against different values of inclination angles and uniform magnetic fields. If the horizontal longitudinal magnetic field is strong enough it extinguishes the convection perturbations along the field direction and stabilizes Rayleigh flows. Observed patterns at about two supercriticalities and with small inclination angles show mostly spatially and temporally chaotic structures.
Magnetic Properties of Frozen Magneto-Active Elastomers
Authors: Stepanov G.V. , Borin Dmitry Yu. , Odenbach Stefan , Gorbunov A.I.
Published: September 2009

In the present paper we report temperature dependent magnetization measurements done on a magneto-active elastomers (MAEs) consisting of a siloxane rubber filled with carbonyl iron particles. The experiments performed in this study are similar to the conventional Zero-Field-Cooled and Field-Cooled magnetic tests. To the best of our knowledge, this approach, successfully used for studies on magnetic fluids, has never ever been applied to MAE. This test allowed us to reveal the effect of change of MAE structure under the action of an external magnetic field.
Effect of Interaction in the Magnetization Reversal Relaxation of Superparamagnetic Granular CoFeB -SiO2 Films
Authors: Timopheev A.A. , Ryabchenko S.M. , Kalita V.M. , Lozenko A.F. , Trotsenko P.A. , Grishin A.M. , Munakata M.
Published: September 2009

In order to study the magnetic interactions influence on the relaxation processes in superparamagnetic media, the magnetostatic measurements were carried out for the granular (CoFeB)x-(SiO2)1-x films with x values near percolation threshold. The observed temperature dependences of the coercivity for the samples magnetized along in-plane easy axis have shown two parts linear on with different inclination angles, which cross each other at the blocking temperature (Tb). The first part of the curve, which corresponds to the temperature range below Tb, depends on the measuring time and is related to the thermal activation nature of magnetization reversal process in the blocked superparamagnetic state. Second part of the curve, which corresponds to the temperature range above Tb, is practically independent on the measuring time and is related to existence of correlated state of superparamagnetic grains moments, i.e. to superferromagnetic state. The method of the magnetization reversal curves simulation based on the numerical solving of kinetic equation has been applied to explain the experimental results.
Magnetoresistive Properties of Tb/Ti and Tb/Si Multilayers
Authors: Svalov Andrey V. , Vas’kovskiy V.O. , Barandiarán José M. , Orue Iñaki , Sorokin A.N. , Kurlyandskaya G.V.
Published: September 2009

Magnetic, magnetoresistive and structural properties of Tb/Ti and Tb/Si nanoscale multilayers prepared by alternative deposition of Tb layers and Ti or Si spacers are comparatively studied. It was concluded that spin disorder scattering is responsible for the negative longitudinal magnetoresistance observed in multilayers of both types.
Finite Size Effects in Field-Induced Transitions in Magnetic Multilayers
Authors: Kostyuchenko Victor V.
Published: September 2009

The technique of finite difference equations is used for an analytical investigation of field-induced transitions in magnetic multilayers. Heisenberg and biquadratic exchange interactions and uniaxial anisotropy are taken into account. The analytical dependencies of critical field values determining the stability of ferromagnetic and antiferromagnetic phases on the layers number are obtained.
Iron-Based Amorphous Magnetic Phase Formation in the Course of Fe and Fe2O3 Mechanical Activation
Authors: Kiseleva Tatiana Yu. , Novakova Alla A. , Chistyakova M.I. , Polyakov A.O. , Gendler Tatiana S. , Grigorieva Tatiana F.
Published: September 2009

Solid phase high energy mechanochemical interaction of α-Fe2O3(hematite) and Fe in powder mixture have been studied. The formation of amorphous iron-based magnetic phase in this process was detected by means of Mossbauer spectroscopy and magnetic measurements. The amount of this phase increases with Fe addition in reduced mixture. Its thermal stability have been studied by magnetic and DCS measurements at constant α-Fe2O3 and gradually increased Fe concentrations.
Magneto-Optical Investigation of Thin-Film Magnetic Systems
Authors: Shalygina Elena E. , Maximova G.V. , Komarova M.A. , Shalygin A.N. , Kozlovskii L.V.
Published: September 2009

Results on the investigation of magnetic and magneto-optical properties of nanocrystalline Fe/Zr and Fe/Zr, Mo/Fe thin-film systems are presented. The examined samples were prepared by DC magnetron sputtering technique. The structural investigations of the samples were performed by X-ray diffraction analysis. The hysteresis loops and spectral dependencies of the transverse Kerr effect were measured employing the magneto-optical magnetometer and the magneto-optical spectrometer, respectively. The influence of the Zr and Mo layer thickness on the magnetic and magneto-optical properties of the examined samples was observed.
Electron Spin Resonance in VOx Nanotubes
Authors: Chernobrovkin A.L. , Semeno A.V. , Glushkov V.V. , Sluchanko N.E. , Samarin N.A. , Demishev S.V. , Grigorieva A.V. , Goodilin E.A.
Published: September 2009

We report the first direct experimental evidence of the presence of antiferromagnetic dimers in VOx nanotubes based on the high frequency (60 GHz) electron spin resonance study carried out in the temperature range of 4.2-200 K. Arguments favouring a possible observation of the low temperature quantum critical phenomena in VOx nanotubes are provided.
Magnetic States of Fe Ions in Fe/Co/Mo Superlattices
Authors: Antipov S.D. , Goryunov G.E. , Granovsky S.A. , Konstantinova E.A. , Smirnitskaya G.V. , Senina V.A. , Stetsenko P. N.
Published: September 2009

In this report the results on the investigation of magnetic states of Fe and Co ions in superlattice [Mo(12Å)Co(21Å)Fe(14Å)]*100 are presented. The magnetic superlattices were obtained by means of cathode sputtering in discharge with oscillating electrons. The results of X-ray diffraction show that magnetic superlattices (MSL) have amorphous state. The magnetic states of Fe and Co ions were investigated using Mössbauer spectroscopy (MS) and electron spin resonance (ESR) for the as-deposited MSL and after annealing at 450°C. The results of our studies of Fe and Co ions states indicate that they correspond to high-spin states in clusters Fen, Com, FenCom, FenMom with small number of atoms n, m in clusters.
Comparative Analysis of γ-Fe2O3 Nanoparticles Magnetic Interactions in Different Polymeric Nanocomposites
Authors: Gendler Tatiana S. , Novakova Alla A. , Prudnikov V.N. , Aleksandrova G.P. , Grishchenko L.A.
Published: September 2009

The comparative study of Fe2O3 4-10nm nanoparticles incorporated in arabinogalactan and polyvinyl alcohol matrixes was performed by means of magnetic measurements in wide 5-900K temperature range, Mossbauer spectroscopy and transmission electron microscopy. The processes of nanoparticles different self-organization inside various polymer matrixes were revealed. These processes lead to unusual magnetic behavior of initially superparamagnetic nanoparticles owing to interparticle interactions.
Investigation of Magnetization Distribution in Co/Au Multilayer Film by Magnetic Force Microscopy
Authors: Nurgazizov N. , Zhdan P. , Kisielewski M. , Stobiecki Feliks
Published: September 2009

Results obtained during examination of the multilayer Co/Au film by different methods of Magnetic Force Microscopy (MFM) are presented. It was shown, that double-pass scanning with MFM tips, characterised by strong magnetic moments resulted in a magnetisation reversal of the sample during MFM imaging. Single pass scanning or use of the MFM tips with low magnetic moments was required to minimise this process. Experimental results demonstrated good correlation between MFM results acquired during single-pass scanning and double-pass scanning with MFM tips characterised by low magnetic moment.
Calculation of Carrier Scattering and Negative Magnetoresistance in Mn-Doped GaAs/InGaAs/GaAs Quantum Well with Ferromagnetism
Authors: Kulbachinskii V.A. , Shchurova L.
Published: September 2009

We have investigated the thermodynamic, transport and magnetotransport properties of free charge carriers in a diluted magnetic semiconductor with a quantum well InGaAs in the GaAs with δ-doped by C and Mn. In order to determine the density of the holes in a quantum well, we carried out thermodynamic calculations of the system of free holes, atoms Mn0 and ions Mn–. We calculated the temperature dependence of resistance and magnetoresistance of holes in the quantum well. The contributions of various scattering mechanisms of holes to the resistance were analyzed. The negative magnetoresistance are explained as the reduction of spin-flip scattering by aligning spins of the magnetic field.
Research of Features Magnetic Permeability and Domain Structures in Fe2O3:GA Crystals near the Morin Transition
Authors: Chzhan A. V. , Vasiliev V.N. , Isaeva T.N. , Patrin G.S.
Published: September 2009

Specially picked up web-chamber is used for visualization of domain structure in hematite. An analysis of domain configuration shows, that domain structure of hematite in a basal plane represents multilayered structure which contains domains both in paralleled thickness and in the parallel basal planes. The temperature features of magnetic permeability and domain structures in Fe2O3:Ga crystals near the Morin transition are investigated. Observable changes of magnetic permeability and changes in domain structure confirm that transition from АFM to WFM occurs in the hematite with Ga impurity as transition of the first sort. Results of research of antiferromagnetic and weakly ferromagnetic resonances (AFMR and WFMR) in these compounds are presented.
Magnetic Properties of Diluted Magnetic Semiconductors Pb1-xVxTe
Authors: Skipetrov E.P. , Zvereva E.A. , Golovanov A.N. , Pichugin N.A. , Primenko A.E. , Savelieva O.A. , Zlomanov V.P. , Vinokurov A.A.
Published: September 2009

The structural and magnetic properties as well as the electron paramagnetic resonance in Pb1-xVxTe (х0.7 at.%) solid solutions have been investigated. It was found that the magnetic field and the temperature dependences of magnetization have a paramagnetic character, connected obviously with the paramagnetic contribution of vanadium impurity isolated ions. Electron paramagnetic resonance spectra were measured and the temperature dependence of the g-factor in the temperature range 85-200 K was obtained.
Influence of Oxygen Contamination on Magnetic Properties of Amorphous and Nanocrystallized FeCuSiNbB Thin Films
Authors: Moulin Johan , Kaviraj Bhaskar , Oubensaïd El Houcine , Alves Francisco , Deshpande Uday P. , Gupta Ajay , Dufour-Gergam Elisabeth
Published: September 2009

Thin films of amorphous FeCuSiNbB alloy have been deposited by RF sputtering with various deposition rates. The bulk oxygen content has been characterized using EDS and XPS. Its dependence on deposition rate shows that water vapour in the sputtering chamber is at the origin of the contamination. It allows also estimating the adsorption coefficient of the oxygen on the sample to be around 15 % at 350 K. The magnetic hardness and the resistivity increase with the contamination in oxygen. In devitrified films, this increase is also related to an enrichment of the residual amorphous matrix in oxygen.
Anomalous Magnetism in Eu(Ca)B6
Authors: Glushkov V.V. , Anisimov M.A. , Bogach A.V. , Demishev S.V. , Samarin N.A. , Kuznetsov A.V. , Dukhnenko A.V. , Levchenko A.V. , Shitsevalova N.Y. , Flachbart K. , Sluchanko N.E.
Published: September 2009

The transport and magnetic properties of the Eu1-xCaxB6 (0x0.4) single crystals were studied in the wide ranges of temperatures (1.8-300 K) and magnetic fields (up to 8 T). The experimental data allow to identify a metal-insulator transition (MIT) at the critical Ca concentration xMIT≈0.3, which agrees well with the predictions of double exchange model (V.M. Pereira et al. Phys. Rev. Lett., 93 (2004) 147202). A significant enhancement of magnetoresistive effect is observed below 100K for Eu1-xCaxB6 compounds corresponding to the metallic side of the MIT (xxMIT). The drastic decrease of paramagnetic Curie temperature evaluated from the magnetic and magnetotransport data is discussed in terms of quantum MIT scenario recently proposed for this low carrier density system.
Novel Ferromagnetic Mn-Doped ZnSiAs2 Chalcopyrite with Curie Point Exceeded Room Temperature
Authors: Marenkin S.F. , Novotortsev V.M. , Fedorchenko I.V. , Varnavskiy S.A. , Koroleva L.A. , Zashchirinskii D.M. , Khapaeva T.M. , Szymczak R.A. , Krzymanska B. , Dobrowolski W. , Kilanski L.
Published: September 2009

Based on Mn-doped chalcopyrite ZnSiAs2 the new dilute magnetic semiconductor with p-type conductivity was produced. The Curie temperature behavior of the produced semiconductor is distinctly dependent on the Mn concentration: 325 K for 1 wt.% and 337 K for 2 wt.% of Mn, consequently. Magnetization, electrical resistance, magnetic resistance and Hall effect of mentioned compositions were studied. Temperature dependence of magnetization M(T) have complicate behavior. For T  15 K the M(T) dependence is characteristic for superparamagnetic and at T > 15 K magnetization is sum of magnetizations of ensemble of superparamagnetic clusters and ferromagnetic phase contained frustration regions.
Influence of Glass Coating Thickness on Magnetoimpedance Ratio in Co-Based Amorphous Microwires
Authors: Antonov A.S. , Buznikov N.A. , D’yachkov A.L. , Furmanova T.A. , Rakhmanov A.A. , Samsonova V.V.
Published: September 2009

The effect of glass coating thickness on the magnetoimpedance in Co-based amorphous microwires was studied. The microwires with different thickness of the glass layer were obtained by means of etching in hydrofluoric acid solution. It was observed that the value of the external mag¬netic field corresponding to the maximum of the impedance decreased with the thickness of the glass layer, whereas the magnetoimpedance ratio did not change significantly. The experimental results are interpreted in terms of changes in the radial distribution of the easy magnetization axes.
The Spectrum of Magnetostatic Waves in Ferromagnetic with Moving Periodical Domain Structure
Authors: Vilkov E.A.
Published: September 2009

The spectral properties of magnetostatic waves in a ferromagnet with a moving periodic domain structure are studied within the exchange-free magnetostatic approximation. It is demonstrated that the Doppler frequency shift caused by the domain-wall motion results in the splitting of the spectrum of each magnetostatic wave mode into two dispersion branches―high-frequency and low-frequency branches. It is found that the more the mode number, the more the separation between these branches with respect to the mode spectrum in the presence of the static domain structure.
PACS numbers: 75.60.-d, 75.60.Ch, 75.70.Kw
Magnetic Resonance and Nature of Magnetism in CeB6
Authors: Demishev S.V. , Semeno A.V. , Bogach A.V. , Samarin N.A. , Ohta H. , Okubo S. , Shitsevalova N.Y. , Sluchanko N.E.
Published: September 2009

We report results of the study of the recently discovered magnetic resonance in CeB6, which is characteristic to the phase II in the magnetic phase diagram of this strongly correlated heavy fermion metal. Experiments were carried out in a wide frequency range /2=44-360 GHz in magnetic field up to 30 T. It is found that the previously reported magnetic resonance exists at all frequencies studied and the g-factor for this resonance increases with frequency from g(/2=44 GHz)~1.55 to g(/2>250 GHz)~1.7. In addition to the aforementioned mode of magnetic oscillations an additional magnetic resonance with the g-factor 1.2-1.3 is detected for the frequencies exceeding 200 GHz. This effect may be a consequence of a complicated magnetic structure of the phase II, which is not foreseen in the standard models of the low temperature magnetic ordering in CeB6.
Metamaterials from Amorphous Ferromagnetic Microwires: Interaction between Microwires
Authors: Ivanov Andrei V. , Shalygin A.N. , Galkin V.Yu. , Vedyayev A.V. , Ivanov V.A.
Published: September 2009

For inhomogeneous mediums the оptical Magnus effect has been derived. The metamaterials fabricated from amorphous ferromagnet Co-Fe-Cr-B-Si microwires are shown to exhibit a negative refractive index for electromagnetic waves over wide scale of GHz frequencies. Optical properties and optical Magnus effect of such metamaterials are tunable by an external magnetic field.
Spontaneous and Field-Induced Magnetic Phase Transitions in Tb1-xRxMn6Sn6 (R = Gd, Y) Compounds
Authors: Mushnikov N.V. , Terent’ev P.B. , Gaviko V.S. , Gerasimov E.G. , Rosenfeld E.V. , Shreder L.A.
Published: September 2009

Magnetization curves and magnetic susceptibility of Tb1 xRxMn6Sn6 (R = Gd, Y) compounds have been measured for aligned powder samples. Concentration dependences of the spin-reorientation transition temperature and temperature dependences of critical fields of the field-induced magnetic transitions have been determined. For the compound Tb0.1Y0.9Mn6Sn6 with the spiral magnetic structure, we found that application of hydrostatic pressure facilitates the ferrimagnetic ordering. This unusual feature is supported by the observation of a large negative spontaneous volume magnetostriction for TbMn6Sn6. The obtained results are discussed in a model considering three different interlayer Mn-Mn exchange interactions in these compounds.
Microwave Properties of Ferromagnetic Nanowires and Applications to Tunable Devices
Authors: Spiegel Judith , Huynen Isabelle
Published: September 2009

Microwave devices as circulators or tunable filters demand nowadays small size and broad bandwidth. Ferromagnetic nanowired membranes are ideal candidates for this purpose. This paper focuses on the dielectric properties of such substrates, as influenced by the ferromagnetic nature of nanowires and their filling factor. Two particular cases are considered: a membrane filled up to its top with nanowires, forming a one-layer substrate, and a membrane filled up to a certain percentage of its height with nanowires, forming a two-layer substrate. The models proposed in this paper for each case take the inductive and gyromagnetic effects in the wires into account. They predict for the one-layer case a magnetodielectric behavior which is tunable by applying an external magnetic field. The effect is no longer visible for the two-layer topology corresponding to microwave circuit applications.
The mmW Band Tamm States in One-Dimensional Magnetophotonic Crystals
Authors: Tarapov Sergey I. , Khodzitskiy M. , Chernovtsev S.V. , Belosorov D. , Merzlikin A.M. , Vinogradov A.P. , Granovsky A.B. , Inoue Mitsuteru
Published: September 2009

The mmW band photonic Tamm states in 1D magnetophotonic crystals are studied. It is shown the possibility to manipulate the eigenfrequencies of such states by an external magnetic field. Our experimental results are in a good agreement with theoretical prediction.
EMR Spectra of Iron-Based Nanoparticles Produced by Dissimilatory Bacteria
Authors: Koksharov Yu.A. , Chistyakova N.I. , Zavarzina D.G. , Treninkov I.A. , Polyakov S.N. , Rusakov V.S.
Published: September 2009

We have studied electron magnetic resonance spectra of iron-oxide nanoparticles related to iron reduction metabolism of dissimilatory bacterium Thermincola ferriacetica. It is found that the resonance parameters of metabolic products change notably with time. The X-ray diffraction data indicates partial crystallization of iron oxide during long time storage under air open conditions.
Crossover from Valence Phase Transition to Kondo Behavior in Yb1-xCexInCu4 as Probed by Cu NQR
Authors: Gippius A.A. , Okhotnikov K.S. , Anferova P.A. , Baenitz M. , Mushnikov N.V. , Vasiliev A.N.
Published: September 2009

Influence of cerium substitution on the valence phase transition in Yb1-xCexInCu4 system (x = 0, 0.04, 0.08, 0.12 and 0.16) has been studied by means of 63Cu NQR. Discontinuous change in Cu NQR frequency was detected around valence transition temperature Tv in YbInCu4, Yb0.96Ce0.04InCu4 and Yb0.92Ce0.08InCu4. In the vicinity of Ce concentration x = 0.08 a crossover from the 1-st order valence phase transition to gradual change of electronic and magnetic properties of Yb1-xCexInCu4 system is observed.
Mössbauer Study of Iron Minerals Formed by Dissimilatory Bacterium
Authors: Chistyakova N.I. , Rusakov V.S. , Koksharov Yu.A. , Zavarzina D.G. , Greneche Jean Marc
Published: September 2009

The kinetics of formation of iron-containing minerals by thermophilic dissimilatory iron-reducing bacteria Themincola ferriacetica (strain Z-0001) has been investigated by Mössbauer spectroscopy. The Mossbauer measurements were performed at room and low (77 and 4.2 K) temperatures and in a magnetic field of 6 T. Electron magnetic resonance (EМR) measurements were also carried out.
Heating in an Alternating Magnetic Field due to Non-Equilibrium Magnetization
Authors: Polyanskiy Vitaliy , Tyatyushkin Alexander
Published: September 2009

Heating of a magnetizable body in an alternating magnetic field near the Curie point due to non-equilibrium magnetizing is theoretically investigated. The body is of a spherical shape and surrounded by a non-magnetizable unbounded medium. The heat generation power density is regarded as a piecewise linear function with a fracture at the Curie point. The steady temperature distribution within the body and outside it is found.
Dependence of Flex on Suspension Capacitance on Human-Body-Model-Electrostatic-Discharge Affected TMR Head
Authors: Jutong N. , Sompongse D. , Rakpongsiri P. , Siritaratiwat Apirat
Published: September 2009

Electrostatic discharge (ESD) effects on GMR recording heads have been reported as the major cause of head failure. Since the information density in hard-disk drives has dramatically increased, the GMR head will be no longer used. The tunneling magnetoresistive (TMR) read heads are initially introduced for a 100 Gbit/in2 density or more. Although the failure mechanism of ESD in GMR recording head has not been explicitly understood in detail, study to protect from this effect has to be undergone. As the TMR head has been commercially started, the ESD effect is closely watched. This is the first time report of the TMR equivalent circuit in order to evaluate the ESD effect. A standard human body model (HBM) is discharged across R+ and R- where the capacitance of flex on suspension (FOS) is varied. It is intriguingly found that the electrical characteristic of the TMR head during discharge period depends on discharge position. This may be explained in terms of asymmetry impedance of TMR by using adapted Thevenin’s theory. The effect of FOS component on TMR recording head is also discussed.
Proximity Effect as a Probe of Electronic Correlations and Exchange Field in Dirty Ferromagnet/Superconductor Nanostructures
Authors: Terentieva Larisa A. , Parfenova Elena L. , Khusainov Mansur G. , Proshin Yurii N.
Published: September 2009

We investigate the interplay between the BCS and 2D Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) states in the dirty thin ferromagnetic metal/superconductor (FM/S) nanostructures. For the FM/S bilayers we have derived the dependencies of critical temperature on the FM layer exchange field, electronic correlations and thickness. Moreover, in the corresponding FM/S/FM trilayers we predict two new π phase superconducting states with electron-electron repulsion in the FM layers. The 2D modulated LOFF states are possible in such trilayers only in presence of a weak magnetic field and at suitable parameters of the FM and S layers. On this base we originally propose the method of proximity effect probe the magnitude and sign of the electronic correlations, the order parameter symmetry and exchange fields in various FM layers.
Ferromagnetism, Antiferromagnetism and Superconductivity in Periodic Table of D.I. Mendeleev
Authors: Koroleva L.I. , Khapaeva T.M.
Published: September 2009

Definite regularity in the distribution of ferromagnetic, antiferromagnetic and superconducting elements is observed in the periodic table starting with the 4-th period. These trends were explained by distinction of degree of division of the d (f)- or р-orbitals of neighboring atoms in the crystal. We calculated also the radii of the external d (f)- and р-orbitals and the nearest to them orbitals with the Slater’s method. It is demonstrated that in the superconducting crystals the d-shells approach the nucleus of neighboring atoms are much closely those for ferromagnetic or antiferromagnetic crystals.
Resistive Transitions in S/F/S Trilayers
Authors: Prischepa Serghej L. , Cirillo Carla , Attanasio Carmine , Vecchione Antonio , Kushnir Vasilij N. , Bell Chris , Aarts Jan , Kupriyanov Mikhail Yu.
Published: September 2009

The phase transition of Nb/Cu0.41Ni0.59/Nb triple layers from the normal to the superconducting state has been studied experimentally by measuring the temperature dependence of the electrical resistance, R(T). It is shown that the shape of the R(T) curves is different depending on the Cu0.41Ni0.59 thickness. To explain the experimental data we developed a qualitative model which makes more evident the interconnection between the superconducting phase transition and the 0 to  crossover in SFS structures.
Properties of Vortex States Induced by Proximity Effect in Hybrid Ferromagnet-Superconductor Systems
Authors: Ader J.P. , Buzdin A.I. , Mel’nikov A.S.
Published: September 2009

We investigate the properties of a thin-walled superconducting shell placed in electrical contact with a ferromagnetic cylinder embedded in the superconductor. The case of a superconductor surrounded by the ferromagnet is also considered. Associated with the orbital effect, spontaneous vortex states may appear, characterized by different winding numbers. Special attention is paid to the switching between states of different vorticities and to the behaviour of the critical temperature caused by an external field.
Magnetic Properties and Structural Transitions in (MnCo)1-xGe
Authors: Markin P.E. , Mushnikov N.V.
Published: September 2009

The magnetic and X-ray diffraction measurements of the ferromagnetic compounds (MnCo)1-xGe have been performed for the concentration range 0 ≤ x ≤ 0.05. The structural and magnetic phase diagrams have been obtained. Compositions for which the magnetic transition from ferromagnetic to paramagnetic state coincides with the structural transition from an orthorhombic to a hexagonal phase have been determined to be 0.015 ≤ x ≤ 0.025. It was found that for the compound with x = 0.015 application of 1 T magnetic field in isothermal regime in the vicinity of the Curie temperature is accompanied by the entropy change 1.3 J/(Kkg).
Monte-Carlo Calculation of the Magnetocaloric Effect in Ni-Mn-Ga Alloys
Authors: Sokolovskiy V.V. , Buchelnikov Vasiliy D. , Taskaev Sergey
Published: September 2009

The three-dimensional model for the theoretical description of the phase transformations and the magnetocaloric effect in shape – memory Heusler Ni2+xMn1-xGa alloys (x=0.18 – 0.27) with a coupled magnetostructural phase transition by the classical Monte Carlo method is proposed. It is shown that the isothermal magnetic entropy change upon magnetic field variations from 0 to 5 T and other magnetic properties are in good agreement with the available experimental data.
Magneto-Optical Effects in Excitonic One-Dimensional Structures
Authors: Erokhin S.G. , Deych L.D. , Lisyansky A.A. , Granovsky A.B.
Published: September 2009

We present results of a theoretical investigation of magneto-optical properties in one-dimensional magnetophotonic crystals containing a quantum well defect. In contrast to garnet based magnetophotonic crystals, our proposed structures can be tuned not only by the magnetic field but also by the electric field, illumination, and irradiation. The developed algorithm can be applied to arbitrary magneto-optical effects in multiple quantum well periodic structures. Using this algorithm we demonstrate that the Fabry-Perot exciton resonator structure significantly enhances the Faraday effect and can be used as a highly efficient modulator of light.
π Phase Superconductivity and Magnetism in Ferromagnet / Superconductor / Ferromagnet Trilayers
Authors: Khusainov Mansur G. , Proshin Yurii N.
Published: September 2009

On the base of new boundary-value problem for the Eilenberger function we investigate the superconducting and magnetic states in ferromagnet/superconductor (FM/S) nanostructures, where superconductivity is a superposition of the BCS pairing with zero total momentum in the S layers and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairing with nonzero 3D coherent momentum k in the FM layers. We originally study the interplay between the BCS and FFLO states in the pure thin FM/S/FM trilayers and two novel -phase superconducting states with electron-electron repulsion in the FM layers are predicted. The modulated FFLO states are possible in such trilayers only in presence of external magnetic field at suitable parameters of the FM and S layers. In the FM/S superlattices there are also two -phase magnetic states (0 and ) with compensation of the exchange field paramagnetic effect. This fact allows us to explain a surprisingly high Tc ~ 5K in the short period Gd/La superlattice and to predict the sign and value of the electron-electron interaction in the ferromagnetic Gd metal.
The Reflectance Spectra of Photonic Crystals with Embedded Ferrite Inclusions
Authors: Gorelik V.S. , Yurasov N.I. , Voinov Y.P. , Samoilovich M.I. , Gryasnov V.V.
Published: September 2009

Results of optical properties investigations of photonic crystals, filled by ferrites, are presented. The photonic crystals consist of amorphous SiO2 spherical nanoclusters. Pores of the crystals were filled by ferrites , where . Reflectance spectra were studied in visible range. It was shown that the reflectivity of the fabricated magnetophotonic crystals increases up to 80% under magnetization.