bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Sintering Temperature on the Microstructure and Electrical Properties of SnO2-Based Varistors
Authors: Hu Guang Liang , Zhu Jian Feng
Published: June 2012

SnO2-based varistors were successfully fabricated from the mixed powders, SnO2, Co2O3, Nb2O5 and Cr2O3. The effects of sintering temperature (1250, 1300, 1350 and 1400 °C) on the microstructure and electrical properties were investigated. The results reveal that the grain size increases with increasing the sintering temperature, and the breakdown electrical filed decreases gradually. When the sintering temperature was 1300 °C, the nonlinear coefficient of the as fabricated SnO2 based varistors presents the maximum of 27. Meanwhile, the leakage current possesses the minimum of 4.5 µA.
Thermoelectric Properties of Solid-State Synthesized Magnesium Silicides Doped with Group BI-III Elements
Authors: You Sin Wook , Choi Soon Mok , Seo Won Seon , Kim Sun Uk , Jang Kyung Wook , Lee Jung Il , Ur Soon Chul , Kim Il Ho
Published: June 2012

Group BI(Cu, Ag)-, BII(Zn)- and BIII(Al, In)-doped Mg2Si compounds were synthesized by solid state reaction and mechanical alloying. Electronic transport properties (Hall coefficient, carrier concentration and mobility) and thermoelectric properties (Seebeck coefficient, electrical conductivity, power factor, thermal conductivity and figure of merit) were examined. Mg2Si powder was synthesized successfully by solid state reaction at 773 K for 6 h and doped by mechanical alloying for 24 h. It was fully consolidated by hot pressing at 1073 K for 1 h. The electrical conductivity increased by doping due to an increase in the carrier concentration. However, the thermal conductivity did not changed significantly by doping, which was due to much larger contribution of the lattice thermal conductivity over the electronic thermal conductivity. Group BIII(Al, In) elements were more effective to enhance the thermoelectric properties of Mg2Si.
Fabrication of Novel Ag-Paste and Evaluation of its Electrical Properties in Bulk-Si Solar Cell
Authors: Jeong Ji Hyun , Kim Sung Jin , Son Chang Rok , Ur Soon Chul , Kweon Soon Young
Published: June 2012

Two kinds of Ag-pastes were prepared for integrating the bulk Si solar cell. One is the Ag-paste mixed with Pb-based glass frit and the other is that mixed with Pb-free glass frit. The major components in the silver paste were 84 wt% Ag, 2 wt% glass frit, 11 wt% solvent of buthyl-cabitol acetate, and 2 wt% the other additives. After fabricating the Ag-pastes, they were coated on the SiNx/n+/p- stacks of a commercial mono-Si substrate. The solar cell efficiency was 17.6% in case of the silver paste mixed with Pb-based glass frit, which was one of the world-best records in the technology. By the way, the efficiency was 16.2% in the solar cell integrated with the silver paste mixed with Pb-free glass frit. The lower performance in the Pb-free Ag-paste was caused by the higher serial resistance and the lower shunt resistance in comparison with the Pb-containing Ag paste.
Development of Nano-Carbon Bucky-Paper Membranes for Membrane Distillation
Authors: Koo Jae Wuk , Han Ji Hee , Lee Sang Ho , Sohn Jin Sik , Choi June Seok
Published: June 2012

Membrane distillation (MD) is a special evaporation process to produce fresh water from seawater or contaminated water using membranes. MD has advantages over other evaporation technologies such as multi-stage flash vaporization (MSF) and multi-effect distillation (MED) due to its relatively low energy requirements, allowing the use of solar energy as its heat source. Nevertheless, lack of membrane materials for MD process hinders its practical implementation for desalination and water treatment. In this study, membranes made of carbon nanotube (CNT) are presented for MD. Flat sheet hydrophobic membranes made of polyvinylidene fluoride (PVDF) were selected as supports for bucky-paper membranes, allowing formation of CNT bucky-paper without chemical reactions. Laboratory-scale systems were used to evaluate their potential and performance in direct contact MD. Water permeability and salt rejection were analyzed for each case. D.I water and synthetic feed water were used for the lab-scale tests. It was demonstrated that the physical immobilization of CNT on a hydrophobic membrane changed led to an increase in vapor permeability while improving salt rejection.
Thermal Decomposition Characteristics of Mg (NO3)2·6H2O and MgCl2·6H2O Composite as Phase Change Material
Authors: Ding Qing , Luo Xue Gang , Lin Xiao Yan
Published: June 2012

The thermal decomposition characteristics of Mg (NO3)2·H2O and MgCl2·6H2O composite were studied by integrated thermal analysis. Results show that there are five steps during the thermal decomposition of phase change material (PCM): the starting temperature of each step is 35.5°C, 93°C, 196°C, 260°C and 318°C, respectively. PCM was calcined at different temperatures at each decomposition step. The composition and morphology of the calcined product was characterized by XRD and SEM. Two major reactions including dehydration and hydrolysis occur in the thermal decomposition progress. Dehydration is the main process below 196 °C, while hydrolysis is predominant process when the temperature is higher than 196 °C.
Influence of Addition of Waste Glass as a Fluxing Agent on the Bloating Phenomenon of Artificial Aggregates Fabricated from Coal Bottom Ash
Authors: Kang Seung Gu , Jo Si Nae , Lee Gi Gang
Published: June 2012

The artificial aggregates (AAs) were manufactured from the parent batch powders consisting of bottom ash produced at thermal power plant and dredged soil by direct sintering method at 1050~1200°C for 10min. The bloating phenomenon could be occurred in AAs due to a gas-capturing caused by large quantity of liquid formed at the specimen surface. Increasing the amount of the Na2O added enlarged the area of black core and size of the macro pores in the aggregates. The inside black core got out of the surface of the specimens sintered at 1200°C showing the rugged and cracked surface, but this morphology did not cause a water absorption to increase.
A Study on the Improvement of Nitrogen Removal Efficiency in Small Size Sewage Treatment Facility Utilizing Zeolite Carrier
Authors: Joo Hyun Jong , Choi Jung Soo , Lee Kwang Hyun , Kim Sung Chul
Published: June 2012

The aim of this research was to develop a zeolite carrier for wastewater treatment in a small-size sewage treatment facility. To evaluate the ion-exchange characteristic of zeolite medium, the isotherm equation of both Langmuir and Freundlich model were examined. It was found that the maximum absorption amount (qm) and adsorption strength (1/n) were about 2.94 mg NH4+-N/g and 0.3854, respectively. In order to validate the adsorption performance by applying the zeolite carrier to the in-situ field, nitrogen removal efficiency was evaluated by a retrofitted process in the small sewage treatment where carbon-nitrogen ratio was especially low in influent. By the application of this proposed method, the effluent TN concentration was in the range of 6.5-20 mg/L (average of 12.9 mg/L) which may satisfy sufficient discharge standard limit. The zeolite medium had ion-exchange capacity of 30-40% of influent NH4+-N concentration, and TN removal efficiency improved about 40% compared to the existing process. Therefore, the renovation of the carrier utilization shows the possibility of pre-treatment of NH4+-N in influent and thus improves the TN removal efficiency of wastewater treatment.
Effect of PE Film Degradation Products on the Carbon Dioxide Content of Soil: A Mathematical Study
Authors: Wu Ji Liang , Luo Xue Gang , Zhang Hong Ping , Lin Xiao Yan
Published: June 2012

The increasing use of the PE plastic film means increasing problems of the soil environmental destroy. In order to investigate the effect of PE film degradation products on the carbon dioxide content of soil, degradation products of the PE film with different molecular weight were added in three kinds of soil respectively, and corns were cultivated in the soil. FTIR gas checkout equipment was utilized to monitor changes of the carbon dioxide content of the different soil. A Mathematical model was built with the recorded data to depict variation of the carbon dioxide content. The results showed that the CO2 content is high in the sandy soil with degradation products of PE plastic films (molecular weight of 5000 Da) . It is also high in the clay soil and loam soil with degradation products of PE (molecular weight of 2000 Da). Compared to the control group (LLDPE), it can be found that small molecular weight PE plastic films have a greater effect on the CO2 content. Thus, it is deduced that small molecular weight PE plastic films are degradable in the soil.
Room-Temperature Ferromagnetism in (III,Mn)Sb Semiconductors
Authors: Danilov Y.A. , Zvonkov B.N. , Kudrin Alexei V. , Vikhrova O.V. , Plankina S.M. , Dunaev V.S. , Nezhdanov A.V. , Drozdov Y.N.
Published: June 2012

t is reported about fabrication by laser deposition in a gaseous environment of epitaxial layers of ferromagnetic semiconductors GaMnSb and InMnSb. Investigations of x-ray diffraction and Raman scattering showed reasonably good crystal quality of GaMnSb and InMnSb layers. Magnetic properties were investigated by magneto-optical transversal Kerr effect and Hall effect. It is established, that GaMnSb layers are ferromagnetic at room temperature. In contrast, InMnSb samples demonstrate the ferromagnetic properties only at low temperatures (< 70 K).
Asymmetric Voltage Behavior of the Tunnel Magnetoresistance in Double Barrier Magnetic Tunnel Junctions
Authors: Useinov A. , Gooneratne C. , Kosel J.
Published: June 2012

In this paper, we study the value of the tunnel magnetoresistance (TMR) as a function of the applied voltage in double barrier magnetic tunnel junctions (DMTJs) with the left and right ferromagnetic (FM) layers being pinned and numerically estimate the possible difference of the TMR curves for negative and positive voltages in the homojunctions (equal barriers and electrodes). DMTJs are modeled as two single barrier junctions connected in series with consecutive tunneling (CST). We investigated the asymmetric voltage behavior of the TMR for the CST in the range of a general theoretical model. Significant asymmetries of the experimental curves, which arise due to different annealing regimes, are mostly explained by different heights of the tunnel barriers and asymmetries of spin polarizations in magnetic layers.
Magnetic Properties and L10 Phase Formation in CoPt Nanoparticles
Authors: Komogortsev S.V. , Chizhik N.A. , Filatov E.Y. , Korenev S.V. , Shubin Y.V. , Velikanov D.A. , Iskhakov Rauf S. , Yurkin G.Y.
Published: June 2012

The effect of the atomic disorderorder transformation on remanence, coercivity and magnetic anisotropy energy in CoPt nanoparticles prepared by thermal decomposition and annealed at 400°C for 4 and 16 hours has been studied. The observed remanence and magnetic anisotropy energy enhancement versus annealing time are discussed in the terms of ordering domain formation inside nanoparticles.
Mössbauer Spectroscopy of Antiferromagnetic Fluctuations in Heavy Fermion CePdSn
Authors: Polikarpov M. A. , Cherepanov V. M. , Chuev M. A.
Published: June 2012

sup>119Sn Mössbauer spectroscopy was used to study the transition from single-ion Kondo behavior in the magnetically ordered state in the heavy-fermion intermetallic СePdSn. Found that the temperature evolution of the experimental spectra agrees with the calculations within the two-level relaxation model. This allows one to treat magnetic structure of CePdSn as the decomposition of the total volume of the СePdSn sample into the antiferromagnetic domains. The temperature dependence of the frequency of fluctuations of the domains magnetization and the distribution density of itinerant electrons near the tin atoms in the process of RKKY interaction are investigated.
Cooperation between K.P. Belov Group and Wrocław Scientific Center
Authors: Suski Wojciech
Published: June 2012

Review of common magnetic and related investigations on the uranium semimetallics and the rare earth intermetallics and their hydrides carried out by K.P. Belov, his students and coworkers as well as by the scientists from Wroc³aw (W. Trzebiatowski's students) is presented.
Ferromodulation Effect Usage for the Magnetic Film Anisotropy Investigation
Authors: Ubizskii S.B. , Pavlyk L.P. , Syvorotka I.I.
Published: June 2012

The ferromodulation effect response model of an anisotropic soft magnetic film placed in the crossed permanent bias and alternating excitation magnetic fields is built. It was shown theoretically and experimentally how such a field configuration can be used for registering the effects relating to the film magnetic anisotropy properties.
The Influence of Magnetoelectric Interactions on the Domain Walls in Multiferroics
Authors: Gareeva Z.V. , Zvezdin A.K.
Published: June 2012

The influence of magnetoelectric interactions on the magnetic structure, flexomagnetoelectric polarization and magnetization in thin multiferroics film has been investigated. The correlation between antiferromagnetic domain structure and ferroelectric domain pattern has been revealed. It has been shown the asymmetry of the antiferromagnetic vector distribution over multiferroics film in the case of 1090 and 710 ferroelectric domain walls. The direction of spins rotation in magnetic domain walls is determined by the type of ferroelectric domains and the antiferromagnetic vector in the centre of ferroelectric domain. The peculiarities of the micromagnetic distribution are reflected in the behavior of polarization and magnetization, which appears to be different for 1800, 1090 and 710 ferroelectric domains.
Coupled R and Fe Magnetic Excitations in RFe3(Bo3)4 Multiferroics
Authors: Kuzmenko A.M. , Mukhin A.A. , Ivanov V.Y. , Bezmaternikh L.N.
Published: June 2012

Various resonance modes were observed in the transmission spectra of rare-earth iron borates RFe3(BO3)4 (R = Nd3+, Sm3+, Gd3+) at the frequency range 100-600 GHz, which were attributed to collective magnetic excitations in the exchange coupled Fe-and R-subsystems, i.e. antiferromagnetic (Fe) resonance and electron transitions in the R-ions. Strong interaction of the Fe and R oscillations was revealed and theoretically analyzed taking into account feature of the R-ion ground state. Intensities of the coupled modes (contributions to magnetic permeability) strongly depend on a difference of Fe and R ions g-factors that allows defining the sign of the latter. In particular, an appreciable intensity of exchange (Nd) modes in NdFe3(BO3)4 is caused by gNd,|| < 0 whereas in GdFe3(BO3)4 with gGd gFe 2 the exchange (Gd) modes were hided due to compensation of Fe and Gd contributions. In SmFe3(BO3)4, despite a negligible Sm g-factor, the Sm modes were clear observed due to their excitation via coupling with the Fe-subsystem.
Charge Density and Density Waves in Vicinity of the Phase Transition to an Incommensurate Magnetic Structure in RMn2O5 Oxides
Authors: Men`shenin V.V. , Nikolaev V.V. , Dmitriev A.V.
Published: June 2012

Physical properties of oxides RMn2O5 (R-rare earth ion) have intensively been studied for the last 15 years. Lately, an increased attention has been drawn to such systems in connection with the discovery in them of a strong relation between long magnetic order and electrical polarization.
Shape Memory Effect in Microsized Samples of Rapidly Quenched Ferromagnetic Alloy Ni-Mn-Ga
Authors: Akatyeva K. , Afonina V. , Albertini F. , von Gratowski S. , Irzhak A. , Fabbrici S. , Khovaylo V. , Koledov V.V. , Krasnoperov E. , Shavrov V.G.
Published: June 2012

The melt spun ribbons of ferromagnetic shape-memory alloy (FSMA) Ni53Mn24Ga23 have been prepared by rapid quenching. Thermomechanical properties have been studied by multi-point technique and perfect shape memory effect (SME) observed. The magnetic field effect on thermomechanical behavior was studied by placing multi-point press into Bitter magnet. A giant (1.2%) bending strain, due to magnetic field-induced martensitic transformation (magnetic-field-induced SME), has been observed at a constant temperature T= 56 °C in a field of 6 T. At least 80% of martensitic transformation reversibly induced by the external field was observed experimentally. Submicron sized samples of the alloy with thicknesses down to 300 nm have been milled by focused ion beam (FIB) technique. The deformation behavior of these samples was studied by Omniprobe micromanipulator in the vacuum chamber of FIB device. The SME response was tested in situ by heating the samples with a semiconductor laser. Strong two-way SME was observed due to bending strains of the samples under study.
Magnetocaloric Effect in Ho-Er-Gd-Co Multicomponent Compounds
Authors: Ćwik J. , Palewski T. , Nenkov K. , Lyubina J. , Gutfleisch Oliver
Published: June 2012

We report magnetic and magnetocaloric properties of polycrystalline series of the (Ho0.9Er0.1)1-xGdxCo2(x = 0.05, 0.1 and 0.15) solid solutions. These samples were synthesized using high purity rare earth metals and cobalt. X-ray diffraction patterns taken at room temperature reveal that all compounds have the C15 cubic Laves phase structure. Magnetization measurements were carried out using a vibration sample magnetometer with a step motor in fields up to 14 T using a Bitter-type magnet. Heat capacity measurements have been performed in the temperature range of 2-300 K without magnetic field and in a magnetic field of 1 and 2 T. The magnetocaloric effect has been estimated in terms of isothermal magnetic entropy change for all solid solutions in magnetic fields up to 3 T. The effect of increasing Gd amount in (Ho0.9Er0.1)1-xGdxCo2on the magnetic and magnetocaloric properties will be discussed.
Magneto-Optical Spectroscopy of Heusler Alloys: Bulk Samples, Thin Films and Microwires
Authors: Novikov A. , Gan'shina E.A. , Granovsky A. , Zhukov A. , Chernenko V.
Published: June 2012

We report magneto-optical spectra of the Heusler bulk alloys Ni-Mn-In, thin films Ni-Mn-Ga, microwires Ni-Mn-In and Ni-Mn-Ga in martensitic and austenitic states. Transversal Kerr effect (TKE) was studied at an angle of light incidence of 68° with respect to the sample plane, in the energy range 0.5 eV < E < 4.0 eV, at 50 350 K temperatures, and in magnetic fields up to 3.5 kOe. The TKE spectra profile does not change too much at martensitic transformation in Ni2MnGa thin films, only magnitudes of characteristic maxima decrease. The magneto-optical response of Ni2MnGa microwires is very similar to that for Ni2MnGa thin films. For most of studied bulk samples, the TKE signal is very weak (about 10-5), about two orders of magnitude smaller than for thin films, and in many cases could not be detected at all. It indicates the strong dependence of the magneto-optical response of Heusler alloys on the quality of optically or electrochemically polished surfaces and their microstructure.
Giant Magnetocaloric Effect in the Region of Magnetic Phase Transition in Mn (As,Sb) Compounds
Authors: Pankratov N.Yu. , Mitsiuk V.I. , Krokhotin A.I. , Smarzhevskaya A.I. , Govor G.A. , Nikitin S.A. , Ryzhkovskii V.M.
Published: June 2012

The MCE in MnAs and doped Mn (As,Sb) compounds with low concentration of Sb has been studied by direct investigation. It was shown that for MnAs the maximum value of MCE is ΔT = 0.28 K on heating (at 308 K) and ΔT = 0.88 K on cooling (at T = 306 K) in magnetic filed 12.5 kOe. In doped Mn (As,Sb) compounds the temperature dependence of MCE is similar to MnAs. All investigated compounds demonstrate a strong temperature and field hysteresis of magnetic properties in magnetic field less than 40 kOe. It was established that a small concentration of Sb leads to decrease of MCE hysteresis and preserves the phase transition at room temperature region.
Magnetocaloric Effect and Magnetic Properties of High Pressure Synthesized RhFe Compound
Authors: Tapas Samanta , Tempel Samuel , Dubenko Igor , Krylov V.I. , Tsvyashchenko A.V. , Fomicheva L.N. , Sadykov R.A. , Ali N.
Published: June 2012

The studies of X-ray diffraction, magnetization, magnetocaloric effect, and 57Fe Mössbauer spectra have been performed in a bulk sample of RhFe compound synthesized under high pressure. It have been found that RhFe has fcc-type of crystal structure at room temperature and, shows the first order magnetic transition from the antiferromagnetic-like to ferromagnetic state close to 338 K at 5T magnetic field. This type of behavior has been verified by differential scanning calorimetry, magnetization and Mössbauer techniques. The irreversible transition from antiferromagnetic to stable ferromagnetic state has been observed after heating of sample up to 573K.
Features of Magneto-Optical Response on Multilayer Nanostructures {(Co45Fe45Zr10)Z(Al2O3)100-Z/α-Si:H}n
Authors: Gan'shina E.A. , Buravtsova Victoria , Novikov A. , Kalinin Y. , Sitnikov A.V.
Published: June 2012

Spectral and field dependencies of Transversal Kerr Effect (TKE) for [(Co45Fe45Zr10)Z(Al2O3)100-Z(X)/α-Si:H(Y)] n multilayers have been studied in the energy range 0.5 - 4.0 eV. It was found that TKE field dependencies in the nearest IR energy range exhibit anomalous behavior for structures only with thin Si layers and this behavior vanishes with increasing of the Si layer thickness. TKE spectra measured in small and large magnetic fields were essentially different. It was shown that magneto-optical response of multilayered structure composite-silicon is the sum of contributions from two composites: (Co45Fe45Zr10) - Al2O3 + Si + silicides and (Co45Fe45Zr10) - Si + silicides, which have a different sign of TKE in the nearest IR spectrum and their magnetic states depend both on composite and semiconducting layer thicknesses.
Effect of the Peierls Relief Chirality on Domain Wall Dynamics in Molecular Ferrimagnet
Authors: Mushenok F.B. , Koplak O.V. , Morgunov R.B. , Chernyshova S.L.
Published: June 2012

In this paper the contributions of switching, slide, creep and Debye relaxation modes of the domain wall dynamics to the low-frequency magnetic properties of chiral and racemic [MnII(HL-pn)(H2O)][MnIII(CN)6]2H2O molecular ferrimagnets were distinguished.
Superconducting Probe of Electronic Correlations and Exchange Field Based on the Proximity Effect in F/S Nanostructures
Authors: Khusainov M. G. , Khusainov M. M. , Proshin Y. N.
Published: June 2012

The proximity effect and competition between the BCS and LOFF states are studied in the Cooper limit for thin F/S and F/S/F nanostructures, where F is a ferromagnet and S is a superconductor. The dependences of the critical temperature Tc on the exchange field I, electron correlations λf, and the thickness df of the F layer are derived for F/S bilayers and F/S/F trilayers. Two new π-phase superconducting states with electronelectron repulsion in the F layers of F/S/F trilayers are predicted. A 2D LOFF state in F/S/F trilayers is possible only in the presence of a weak magnetic field and the appropriate parameters of the F and S layers. The absence of the suppression of 3D superconductivity in short-period Gd/La superlattices is explained and the electronelectron coupling constant in gadolinium is predicted. A method of superconducting probe spectroscopy based on the proximity effect is proposed for determining the symmetry of the order parameter, the magnitude and sign of electron correlations, and the exchange field in various nanomagnets F.
Magnetic Properties and Thermal Stability of xFe (100-x)SiO2 (x=5-95) Powder Nanocomposites
Authors: Kiseleva Tatiana Yu. , Novakova Alla A. , Gendler Tatiana S. , Il’inych Igor A. , Levina Vera V.
Published: June 2012

The study of Fe/SiO2nanocomposites magnetic properties and structure relationships was performed in dependence on Fe to SiO2relative concentration and type of precursors preparation (mechanical mixing or ultrasonic homogenization). Thermal metallization method in hot hydrogen of initial reagents [хFeOOH and (100-x)SiO2] was applied for nanocermets production. It was determined that formation of air-tight shell on the particles surface affects the nanocomposites magnetization values and their air temperature stability.
Тunneling of Acoustic Waves through the Gap between Two Ferromagnetic Crystals with the Relative Longitudinal Motion
Authors: Moiseev A. , Vilkov E.A.
Published: June 2012

The tunneling of a plane monochromatic acoustic wave through a gap between two ferromagnets under conditions of their relative longitudinal displacement has been considered. It has been shown that, the inclusion of the longitudinal displacement of one of the crystals, in all cases, leads to the violation of resonance conditions and, consequently, to a noticeable decrease in the coefficient of transmission of the acoustic wave through the gap between two ferromagnets; this effect is more pronounced, the higher is the velocity of motion of the crystal. It has been demonstrated that there is a possibility of the wave front reversal occurring with the amplification of the reflected magnetoacoustic wave.
"γ-Fe Problem" and Epitaxial Growth of Fe on Cu(001)
Authors: Myagkov V.G. , Bayukov O.A. , Zhigalov V.S. , Bykova L.E. , Drozdova N.A. , Bondarenko G.N.
Published: June 2012

We have observed the formation of a thin buffer layer on the Fe/Cu interface at a temperature of 520 K. Mössbauer spectroscopy and magnetic studies reveal that the residual gases in the chamber (especially oxygen) play an important role in the ultra-thin interlayer formation. It was shown that the Cu2O buffer layer does not change the Pitsh orientation relationships during epitaxial growth of α-Fe (110) on Cu (001). Our analysis of the experimental results contradicts pseudomorphic growth and formation of γ-Fe on Cu (001).
Magneto-Optical Kerr Effect Enhancement in Co-Ti-O Nanocomposite Films
Authors: Polyakov V.V. , Polyakova K.P. , Seredkin V. A. , Patrin G.S.
Published: June 2012

Co-Ti-O nanogranular films with different volume concentrations of a magnetic phase and Co/Ti-O layered structures with different numbers of layer pairs are studied by the magneto-optical Kerr effect. It is shown that, unlike the case of homogeneous metal films, the magneto-optical spectra of the nanogranular films exhibit resonance with a significant increase in the Kerr rotation angle in the wavelength range 500-700 nm. It is found that the Kerr rotation angle of the Co/Ti-O layer structures in the wavelength range 500-600 nm grows by an order of magnitude as compared to its value for ordinary Co films.
Extended Dynamic Spin-Fluctuation Theory with Application to Iron
Authors: Reser B.I. , Melnikov N.B. , Grebennikov Vladimir I.
Published: June 2012

The problem of discontinuous phase transition in the dynamic spin-fluctuation theory is resolved by taking into account large anharmonic spin fluctuations and nonlocality of the mean Green function. The extended theory is applied to the calculation of magnetic properties of iron.
GaAs:Mn Layer Magnetization in GaAs-Based Heterostructures Containing InGaAs Quantum Well
Authors: Dmitriev A.I. , Koplak O.V. , Morgunov R.B.
Published: June 2012

Magnetic properties of a GaAs-based heterostructures containing InGaAs quantum well and 2 nm thick GaAs layer doped with 5 at. % Mn (GaAs:Mn) on flat and vicinal substrates were studied. Two types of ferromagnetism were found. In the heterostructures grown on the flat substrate parallel to the (001) GaAs plane the magnetization obeys the Bloch T3/2 temperature dependence while for the structures grown on the vicinal surface grown (disoriented by 3°) the magnetization follows percolation dependence.
Exchange Enhancement of g-Factor in Narrow-Gap InAs/AlSb Quantum Well Heterostructures
Authors: Krishtopenko S.S. , Gavrilenko V.I. , Goiran M.
Published: June 2012

We report on the study of exchange enhancement of g-factor in 2D electron gas in n-type narrow-gap semiconductor heterostructures that feature a strong nonparabolicity of electric subbands. We demonstrate that exchange g-factor enhancement not only shows maxima at odd values of Landau level filling factors but, due to subband nonparabolicity, persists at even filling factor values as well. The magnitude of the exchange enhancement, the amplitude and shape of the g-factor oscillations are governed by both the screening of electron-electron interaction and the Landau level width. The enhanced g-factor values calculated for 2D electron gas in InAs/AlSb quantum well heterostructures are compared with previous experimental magnetotransport data.
Structure, Magnetic and Microwave Properties of Granular Fex(SiO2)1-x Alloys Obtained by Mechanochemical Synthesis
Authors: Lomayeva S.F. , Maratkanova A.N. , Rozanov Konstantin N. , Petrov D. A. , Yelsukov Eugene P.
Published: June 2012

The structural-phase composition, magnetic and microwave properties of Fex(SiO2)1-x (x=30, 70, 90, 95) nanocomposites have been studied. The composites are produced by high-energy ball milling with either Ar or acetone as a milling medium and milling time of 1 to 64 h. The microwave magnetic properties of the composite in the frequency range of 0.1 to 6 GHz are shown to depend slightly on the phase composition and be governed mainly by the particle size. Reduction of the particle size to about 1 μm results in elimination of magnetic loss at frequencies below 1 GHz, which is attributed to the domain walls motion.
Spectral Properties of Superlattices with Anisotropic Inhomogeneities. The Transition from 3D to 2D Disorder
Authors: Ignatchenko V.A. , Pozdnyakov A.V.
Published: June 2012

Waves in superlattice (SL) contained inhomogeneities with anisotropic correlation properties are considered. The anisotropy of the correlation during the transition from 3D to 2D disorder is characterized by the parameter , where and are the correlation wave numbers along the axis of the SL and in the plane of the its layers, respectively ( and are the correlation radii). Dependencies of both the dynamic susceptibility and density of states at the continuous transition from the isotropic three-dimensional inhomogeneities () to the two-dimensional ones () have been obtained.
ESR Spectra of Charge Carriers in the α'- and β- Phases of (BEDT-TTF)2IBr2 Single Crystals
Authors: Chernenkaya A. , Dmitriev A.I. , Kirman M. , Koplak O.V. , Morgunov R.B.
Published: June 2012

High-frequency dynamic magnetic properties of quasi-two-dimensional organic conductors (BEDT-TTF)2IBr2ofα'- andβ-phases have been studied by Electron Spin Resonance (ESR) spectroscopy. The heating of crystals in theα'-phase is accompanied by their phase transition to theβ-phase, so, the Dyson distortion of the ESR line is appeared. Contributions from the crystal field and symmetry of the system as well as the orbital magnetic moment admixture to the total magnetic moment of charge carriers have been judged by the comparison of the orientation and temperature dependencies of the ESR spectra for theα'- andβ-phases. Experimental data have proved localized states of charge carriers either inα'- orβ-phases.
Transitions in There-Dimensional Magnets with Extra Broken Symmetry
Authors: Sorokin A.O. , Syromyatnikov A.V.
Published: June 2012

We introduce and investigate a few models of three-dimensional frustrated magnets withpossible new pseudo-universal behavior appearing upon a phase transition of weak first order.We an-alyze the different broken symmetry scenarios implemented in frustrated XY and Heisenberg magnetsto compare with our results.
Magnetic Exchange Interactions and Supertransferred Hyperfine Fields at 119Sn Probe Atoms in CaCu3Mn4O12 Manganite
Authors: Rusakov V.S. , Presniakov I.A. , Sobolev A.V. , Demazeau Gérard , Gapochka A.M. , Gubaidulina T.V. , Matsnev M.E. , Volkova O.S. , Vasil'ev A.N.
Published: June 2012

The hyperfine magnetic interactions of 119Sn probe atoms in the CaCu3Mn3.96Sn0.04O12 double manganite by Mössbauer spectroscopy using magnetic measurements have been investigated. A consistent description of the results obtained in terms of the Weiss molecular field model by taking into account the peculiarities of the local environment of tin atoms has allowed the indirect Cu2+OMn4+ (JCuMn 51 ± 1 K) and Mn4+OMn4+ (JMnMn 0.6 ± 0.6 K) exchange interaction integrals to be estimated. Based on the KanamoriGoodenoughAnderson model, we show that the magnitude and sign of the intrasublattice exchange integral JMnMn correspond to both the electronic configuration of the Mn4+ cations and the geometry of their local crystallographic environment in the compound under study.
Spontaneous Generation of Voltage in Sm0.55Sr0.45MnO3 and La0.75Ba0.25MnO3 Single Crystals
Authors: Zashchirinskii D.M. , Koroleva L.I. , Morozov A.S.
Published: June 2012

In Sm0.55Sr0.45MnO3single crystals, grown by the floating-zone method with the cooling in oxygen, has been observed the spontaneous generation of voltage (SGV). Its maximum reaches 60 μV and occurs in the temperature range where simultaneous decay of the CE-type antiferromagnetic order and the charge order take place in some clusters. The SGV peak becomes lower by about 45% if magnetic field 14.2 kOe applied. Also we observed the SGV in La0.75Ba0.25MnO3single crystals. Maximum value of SGV occurs in a vicinity of the Curie temperature. The SGV value seems to be almost independent from the cooling or heating rate and crystallographic direction, but in La0.75Ba0.25MnO3it is smaller than in Sm0.55Sr0.45MnO3by an order of magnitude. La0.75Ba0.25MnO3compound contains ferromagnetic clusters, in which the electrical charges are localized according to gain in thes-dexchange energy. They are distributed in the paramagnetic lattice, impoverished of an electrical charge. It is shown that SGV stems from the presence of regions with different electrical charges in both samples.
Study of Nature of Paramagnetic Doublet in Mössbauer Spectra of Mice Liver Using External Magnetic Field
Authors: Gabbasov R.R. , Cherepanov V. M. , Chuev M. A. , Polikarpov M. A. , Nikitin Maxim P. , Deyev S.M. , Panchenko V.Y.
Published: June 2012

A process of the biodegradationin vivoof a magnetic ferrofluid was investigated by Mössbauer spectroscopy. After the injection of the ferrofluid in a mice body an additional doublet was observed in the Mössbauer spectra of the mice liver. Further analysis showed that the doublet consists of two components with different magnetic properties. The components related both to the formation of non-magnetic ferritin-like proteins and superparamagnetic behavior of the injected nanoparticles. These components were separated in an external magnetic field and the time evolution of each fraction was studied. The concentration of both of these fractions in the frame of multi-level relaxation model was estimated.
Magneto-Optic Fraunhofer Diffraction on 2D Magnetic Domain Patterns
Authors: Logunov M. , Nikitov S.A. , Gerasimov M. , Kashkin D. , Loginov N. , Spirin A.
Published: June 2012

Magneto-optical Fraunhofer diffraction on phase 2D domain patterns with Cmm6 and Pab2 symmetry in uniaxial iron garnet films was studied. Domain patterns contain more than 100 elementary cells and have high spatial homogeneity. The diffraction patterns contain up to 10 or more orders of peaks. Possibilities of space-time modulation of optical radiation and multiplication of the modulation frequency both under change of diffraction order as well as amplitude of magnetic bias field strength were shown.
Suppression of Ferromagnetism in EuxCa1-xB6
Authors: Glushkov V.V. , Kuznetsov A.V. , Sannikov I. , Bogach A.V. , Demishev S.V. , Ivanov V.Y. , Dukhnenko A.V. , Levchenko A.V. , Shitsevalova N.Y. , Sluchanko N.E.
Published: June 2012

We report the magnetic properties of EuxCa1-xB6single crystals (0.756x1) studied in the wide range of temperatures (1.8-300 K) and magnetic fields (up to 50 kOe). It was found that low field magnetic susceptibility χ (T) follows the Curie-Weiss law χ~(T-Θp)-1at high temperatures for all the concentrations studied. The effective magnetic moment of the Eu2+ion estimated from the data diminishes from the free ion value μeff7.93μB(μB- Bohr magneton) for x=1 to μeff7.3μBfor x=0.756. A universal behavior of magnetic susceptibility χ~(T-Θ)-α(α=1.5) is detected close to the Curie temperature TCin the paramagnetic state at both metallic (x>xC~0.8) and dielectric (xC.
Retinoic Acid Attenuates Rheumatoid Inflammation in Mice
Authors: Kwok Seung-Ki , Park Mi-Kyung , Cho Mi-La , Oh Hye-Jwa , Park Eun-Mi , Lee Dong-Gun , Lee Jennifer , Kim Ho-Youn , Park Sung-Hwan
Published: June 2012

Retinoic acid is the active vitamin A derivative and is well-known to have diverse immunomodulatory actions. In this study, we investigated the impact of all-trans retinoic acid (ATRA), a biologic key metabolite of vitamin A, on the development of arthritis and the pathophysiologic mechanisms by which ATRA might have antiarthritic effects in animal model of rheumatoid arthritis (RA; collagen-induced arthritis [CIA] in DBA/1J mice). We showed that treatment with ATRA markedly suppressed the clinical and histologic signs of arthritis in the CIA mice. It reduced the expression of IL-17 in the arthritic joints. Interestingly, Foxp3+ regulatory T cells were markedly increased and IL-17–producing CD4+ T cells (Th17 cells) were decreased in the spleens of ATRA-treated mice. In vitro treatment with ATRA induced the expression of Foxp3 and repressed the IL-17 expression in the CD4+ T cells in mice. ATRA suppressed the production of total IgG and IgG2a in splenocytes that were stimulated by LPS. It also reduced serum levels of total IgG and IgG2 anti-collagen Abs and germinal center formation in CIA mice. In addition, the ATRA-treated mice showed decreased osteoclast formation in arthritic joints. Moreover, ATRA downregulated the expression of receptor activator of NF-κB ligand, the leading player of osteoclastogenesis, in the CD4+ T cells and fibroblast-like synoviocytes from patients with RA. Furthermore, ATRA prevented both human monocytes and mice bone marrow-derived monocytes/macrophage cells from differentiating into osteoclasts. These data suggest ATRA might be an effective treatment modality for RA patients.
Modelling Trades-Through in a Limit Order Book Using Hawkes Processes
Authors: Toke Ioane Muni , Pomponio Fabrizio
Published: June 2012

The authors model trades-through, i.e. transactions that reach at least the second level of limit orders in an order book. Using tick-by-tick data on Euronext-traded stocks, they show that a simple bivariate Hawkes process fits nicely their empirical observations of tradesthrough. The authors show that the cross-influence of bid and ask trades-through is weak.
Long-term dust climatology in the western United States reconstructed from routine aerosol ground monitoring
Authors: Tong D. Q. , Dan M. , Wang T. , Lee P.
Published: June 2012

Abstract. This study introduces an observation-based dust identification approach and applies it to reconstruct long-term dust climatology in the western United States. Long-term dust climatology is important for quantifying the effects of atmospheric aerosols on regional and global climate. Although many routine aerosol monitoring networks exist, it is often difficult to obtain dust records from these networks, because these monitors are either deployed far away from dust active regions (most likely collocated with dense population) or contaminated by anthropogenic sources and other natural sources, such as wildfires and vegetation detritus. Here we propose an approach to identify local dust events relying solely on aerosol mass and composition from general-purpose aerosol measurements. Through analyzing the chemical and physical characteristics of aerosol observations during satellite-detected dust episodes, we select five indicators to be used to identify local dust records: (1) high PM10 concentrations; (2) low PM2.5/PM10 ratio; (3) higher concentrations and percentage of crustal elements; (4) lower percentage of anthropogenic pollutants; and (5) low enrichment factors of anthropogenic elements. After establishing these identification criteria, we conduct hierarchical cluster analysis for all validated aerosol measurement data over 68 IMPROVE sites in the western United States. A total of 182 local dust events were identified over 30 of the 68 locations from 2000 to 2007. These locations are either close to the four US Deserts, namely the Great Basin Desert, the Mojave Desert, the Sonoran Desert, and the Chihuahuan Desert, or in the high wind power region (Colorado). During the eight-year study period, the total number of dust events displays an interesting four-year activity cycle (one in 2000–2003 and the other in 2004–2007). The years of 2003, 2002 and 2007 are the three most active dust periods, with 46, 31 and 24 recorded dust events, respectively, while the years of 2000, 2004 and 2005 are the calmest periods, all with single digit dust records. Among these deserts, the Chihuahuan Desert (59 cases) and the Sonoran Desert (62 cases) are by far the most active source regions. In general, the Chihuahuan Desert dominates dust activities in the first half of the eight-year period while the Sonoran Desert in the second half. The monthly frequency of dust events shows a peak from March to July and a second peak in autumn from September to November. The large quantity of dust events occurring in summertime also suggests the prevailing impact of windblown dust across the year. This seasonal variation is consistent with previous model simulations over the United States.
Signals of El Niño Modoki in the tropical tropopause layer and stratosphere
Authors: Xie F. , Li J. , Tian W. , Feng J. , Huo Y.
Published: June 2012

Abstract. The effects of El Niño Modoki events on the tropical tropopause layer (TTL) and on the stratosphere were investigated using European Center for Medium Range Weather Forecasting (ECMWF) reanalysis data, oceanic El Niño indices, and general climate model outputs. El Niño Modoki events tend to depress convective activities in the western and eastern Pacific but enhance convective activities in the central and northern Pacific. Consequently, during El Niño Modoki events, negative water vapor anomalies occur in the western and eastern Pacific upper troposphere, whereas there are positive anomalies in the central and northern Pacific upper troposphere. The spatial patterns of the outgoing longwave radiation (OLR) and upper tropospheric water vapor anomalies exhibit a tripolar form. The empirical orthogonal function (EOF) analysis of the OLR and upper tropospheric water vapor anomalies reveals that canonical El Niño events are associated with the leading mode of the EOF, while El Niño Modoki events correspond to the second mode. The composite analysis based on ERA-interim data indicate that El Niño Modoki events have a reverse effect on middle-high latitudes stratosphere, as compared with the effect of typical El Niño events, i.e., the northern polar vortex is stronger and colder but the southern polar vortex is weaker and warmer during El Niño Modoki events. According to the simulation' results, we found that the reverse effect on the middle-high latitudes stratosphere is resulted from a complicated interaction between quasi-biennial oscillation (QBO) signal of east phase and El Niño Modoki signal. This interaction is not a simply linear overlay of QBO signal and El Niño Modoki signal in the stratosphere, it is El Niño Modoki that leads to different tropospheric zonal wind anomalies with QBO forcing from that caused by typical El Niño, thus, the planetary wave propagation from troposphere to the stratosphere during El Niño Modoki events is different from that during canonical El Niño events. However, when QBO is in its west phase, El Niño Modoki events have the same effect on middle-high latitudes stratosphere as the typical El Niño events. Our simulations also suggest that canonical El Niño and El Niño Modoki activities actually have the same influence on the middle-high latitudes stratosphere when in the absence of QBO forcing.
Temporal evolution of stable water isotopologues in cloud droplets during HCCT-2010
Authors: Spiegel J. K. , Aemisegger F. , Scholl M. , Wienhold F. G. , Collett J. L. , Lee T. , van Pinxteren D. , Mertes S. , Tilgner A. , Herrmann H. , Werner R. A. , Buchmann N. , Eugster W.
Published: June 2012

Abstract. In this work, we present the first study resolving the temporal evolution of δ2H and δ18O values in cloud droplets during the course of 13 different cloud events. The cloud events were probed on a 937 m high mountain chain in Germany in the framework of the Hill Cap Cloud Thuringia 2010 campaign (HCCT-2010) in September and October 2010. δ values of cloud droplets ranged from −77‰ to −15‰ (δ2H ) and from −12.1‰ to −3.9‰ (δ18O) over the whole campaign. The cloud water line of the measured δ values was δ2H=7.8×δ18O+13×10−3 which is of similar slope but with higher deuterium excess (d-excess) than Central European Meteoric Water Lines. While seasonality was reflected in decreasing δ values towards the colder season, d-excess of cloud samples was an indicator of air mass origin: polar air masses had a higher d-excess than Mediterranean air masses. The variations in δ values during one cloud event could either result from changes in meteorological conditions during condensation or from variations in δ values of the water vapor feeding the cloud. To test which of both aspect dominated during the measured cloud events, we modeled the variation in δ values in cloud water using a closed box model. We could show that the variation in δ values of two cloud events was mainly due to changes in local temperature conditions. For the other eleven cloud events the variation was most likely caused by changes in the isotopic composition of the advected and entrained vapor. Frontal passages led to the highest gradients both in δ2H (≈6‰ per hour) and δ18O (≈0.6‰ per hour) during two of the latter cloud events. Moreover, a detailed trajectory analysis for the two longest cloud events revealed that variations in the entrained vapor were most likely related to rain out or changes in relative humidity and temperature at the moisture source region or both. This study illustrates the sensitivity of stable isotope composition of cloud water to changes in large scale air mass properties.
A simple empirical model estimating atmospheric CO2 background concentrations
Authors: Reuter M. , Buchwitz M. , Schneising O. , Hase F. , Heymann J. , Guerlet S. , Cogan A. J. , Bovensmann H. , Burrows J. P.
Published: June 2012

Abstract. A simple empirical CO2 model (SECM) is presented to estimate column-average dry-air mole fractions of atmospheric CO2 (XCO2) as well as mixing ratio profiles. SECM is based on a simple equation depending on 17 empirical parameters, latitude, and date. The empirical parameters have been determined by least squares fitting to NOAA's (National Oceanic and Atmospheric Administration) assimilation system CarbonTracker version 2010 (CT2010). Comparisons with TCCON (total carbon column observing network) FTS (Fourier transform spectrometer) measurements show that SECM XCO2 agrees quite well with reality. The synthetic XCO2 values have a standard error of 1.39 ppm and systematic station-to-station biases of 0.46 ppm. Typical column averaging kernels of the TCCON FTS, a SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY), and two GOSAT (Greenhouse gases Observing SATellite) XCO2 retrieval algorithms have been used to assess the smoothing error introduced by using SECM profiles instead of CT2010 profiles as a priori. The additional smoothing error amounts to 0.17 ppm for a typical SCIAMACHY averaging kernel and is most times much smaller for the other instruments (e.g. 0.05 ppm for a typical TCCON FTS averaging kernel). Therefore, SECM is well suited to provide a priori information for state-of-the-art ground-based (FTS) and satellite-based (GOSAT, SCIAMACHY) XCO2 retrievals. Other potential applications are: (i) near real-time processing systems (that cannot make use of models like CT2010 operated in delayed mode), (ii) "CO2 proxy" methods for XCH4 retrievals (as correction for the XCO2 background), and (iii) observing system simulation experiments especially for future satellite missions.