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Concentration and angular dependences of the parameters (line width and position) of ferromagnetic resonance (FMR) for CoTaNb/MgO composite films with metal alloy concentrations x = 0.27–0.72 were obtained in the work. Granular, granular-percolation structure and zigzag stripe magnetic structure for films with different x were detected. An increase in the FMR parameters with an increase in the angle from 0° to 90° between the constant magnetic field and the film plane with different x was observed. It was shown in the work that the behavior of the angular dependences strongly depends on the magnetic structure of the films, which have the greatest change in the region of transition from granular to granular-percolation structure with extended magnetic metallic microregions. The FMR method is a structure-sensitive method for scientific studies of the electromagnetic properties of thin magnetic composite films with granular and percolation structures and their combinations was demonstrated. [ABSTRACT FROM AUTHOR]

The paper reveals the influence of Li, B and the composition of metal contacts on the processes of resistive switching in memristive structures M/NC/D/M. After field exposure in structures Cu/(Co50Fe50)x(LiNbO3)100–x/s-LiNbO3/Cu/sitall, Cu/(Co50Fe50)x(LiNbO3)100–x/d-LiNbO3/Cu/sitall and Cu/(Co40Fe40B20)x(SiO2)100–x/d LiNbO3/Cu/sitall at x < 13 was detected a residual voltage (up to 16 mV) due to the electromigration of Li ions, that leading to a "reversible" type of VAC hysteresis and instability of the time dependencies of induced resistive states. In the structures of Cu/(Co40Fe40B20)x(LiNbO3)100–x/s-LiNbO3/Cu/sitall, Cr/Cu/Cr/(Co40Fe40B20)x(LiNbO3)100–x/s-LiNbO3/Cr/Cu/Cr/sitall containing B, the residual voltage is reduced by formation of chemical compounds B with percolated Li atoms. When limiting the electromigration of Li ions, the main mechanism of resistive switching is the processes of electromigration of oxygen vacancies in the dielectric oxide layer. Suppression of residual voltage in the Cr/Cu/Cr/(Co50Fe50)x(LiNbO3)100–x/s-LiNbO3/Cr/Cu/Cr/sitall structure due to the introduction of a Cr buffer layer that does not dissolve Li leads to the absence of bipolar resistive switching in these structures. [ABSTRACT FROM AUTHOR]

The paper reveals the influence of Li, B and the composition of metal contacts on the processes of resistive switching in memristive structures M/NC/D/M. After field exposure in structures Cu/(Co50Fe50)x(LiNbO3)100–x/s-LiNbO3/Cu/sitall, Cu/(Co50Fe50)x(LiNbO3)100–x/d-LiNbO3/Cu/sitall and Cu/(Co40Fe40B20)x(SiO2)100–x/d LiNbO3/Cu/sitall at x < 13 was detected a residual voltage (up to 16 mV) due to the electromigration of Li ions, that leading to a "reversible" type of VAC hysteresis and instability of the time dependencies of induced resistive states. In the structures of Cu/(Co40Fe40B20)x(LiNbO3)100–x/s-LiNbO3/Cu/sitall, Cr/Cu/Cr/(Co40Fe40B20)x(LiNbO3)100–x/s-LiNbO3/Cr/Cu/Cr/sitall containing B, the residual voltage is reduced by formation of chemical compounds B with percolated Li atoms. When limiting the electromigration of Li ions, the main mechanism of resistive switching is the processes of electromigration of oxygen vacancies in the dielectric oxide layer. Suppression of residual voltage in the Cr/Cu/Cr/(Co50Fe50)x(LiNbO3)100–x/s-LiNbO3/Cr/Cu/Cr/sitall structure due to the introduction of a Cr buffer layer that does not dissolve Li leads to the absence of bipolar resistive switching in these structures. [ABSTRACT FROM AUTHOR]

The optical and electrical properties of bismuth ferrite thin films obtained by high-frequency magnetron sputtering in an atmosphere of argon and oxygen (80% + 20%) has been studied. Investigations of the optical properties have shown that for polycrystalline bismuth ferrite films the optical band gap is ~2.3 eV, which is in the range of given in the literature values. The dependences of the specific electrical conductivity on the magnitude of the electric field has been studied for the synthesized films. It has been established that the electrical conductivity does not depend on the electric field strength up to the value of E = 2.1 × 106 V/m. The experimental results are discussed in terms of the model of charge carrier injection from aluminum electrode into the conduction band of bismuth ferrite. [ABSTRACT FROM AUTHOR]

The topological features of the formation of (Co40Fe40B20)15(LiNbO3)85 composite films deposited by ion-beam method on a metal electrode Cr/Cu/Cr has been investigated. The presence of a dielectric layer between the upper Cr layer and the CoFe–LiNbO3 film with a thickness of dox ≈ 15 nm has been established. The difference in the size of granules near the amorphous layer and in the volume of the film has been shown. A model of the formation of (Co40Fe40B20)x (LiNbO3)100 –x nanocomposite film at the initial stage of growth has been proposed. It has been shown that the formation of α-LiNbO3 layer on the chrome metal film surface is possible with the realization of island and layer-by-layer growth mechanisms for various phases of the composite. [ABSTRACT FROM AUTHOR]

Optical and electrical properties of cobalt oxide thin films obtained by ion-beam sputtering in argon atmosphere and argon with the addition of oxygen (PAr = 1.1 × 10–5 Torr) has been investigated in the work. Optical properties investigations showed that, for films of cobalt oxide obtained in argon atmosphere, the optical band gap is independent of the film thickness and is 3.24 eV, which is in the range of given in the literature for the CoO phase values. For cobalt oxide films obtained in mixed atmosphere of argon with the addition of oxygen, two direct optical transitions with energies of 1.45 and 2.1 eV were detected. The presence of two direct allowed optical transitions is associated with the variable valence of cobalt in the Co3O4 compound and the presence of two valence states Co2+ and Co3+. The dependences of specific electrical conductivity of the synthesized films on the magnitude of the electric field were studied. It was found that for all investigated samples, the electrical conductivity does not depend on the electric field strength up to the value of E = 106 V/m. The nonlinearity of the dependence of specific electrical conductivity of the synthesized films on electric field strength at E > 106 V/m is discussed in terms of the hopping conductivity model and the trap ionization model described by the Poole–Frenkel effect. [ABSTRACT FROM AUTHOR]

It is found that (CoFeB + SiO2) composite films have a narrow spread of film surface protrusions at low concentrations of the metal alloy (x < 0.35), while a wider spread and smooth distribution of the protrusions are observed at the large concentration (x > 0.53). It is shown that the concentration dependence of the ferromagnetic resonance linewidth has a maximum at x = 0.45, due to the percolation structure of the films. [ABSTRACT FROM AUTHOR]

Microwave magnetic impedance spectra are obtained for (x = 0.46–0.88) films in a DC magnetic field of 0‒0.7 T. The modulus of microwave impedance in films with x = 0.76 is found to fall by as much as 6% upon magnetization. The maximum negative microwave magnetic impedance of the films is established along with its shift from 2.2 to 0.4 GHz as x rises. A striped magnetic structure with oppositely directed magnetizations of neighboring stripes is observed. [ABSTRACT FROM AUTHOR]

The effect of oxygen and water vapor in a sputtering chamber during the deposition of thin-film (Co40Fe40B20)x(LiNbO3)100 –x nanocomposites on the electrical properties of the heterogenous system is investigated. It is found that the resistivity of (Co40Fe40B20)x(LiNbO3)100 –x nanocomposites increases significantly with the partial pressure of reactive gases (oxygen and water vapor). A noticeable shift of the percolation threshold towards higher values of the metal phase volume concentration, which is observed in the plane of the film and in the perpendicular direction during the synthesis of composites with the addition of reactive gases, is attributed to the increase in the volume concentration of the dielectric phase. It is found that the percolation threshold for the measurements in the geometry perpendicular to the plane of the film is characterized by a much lower concentration of the Co40Fe40B20 alloy atoms than that for the measurements in the plane of the film, which is associated with an elongated shape of granules in the film growth direction and the effects of Coulomb blockade suppression by a high transverse electric field. [ABSTRACT FROM AUTHOR]

The internal friction spectra of cured epoxy T-107 and a fiberglass reinforced plastic based on it are studied. In the temperature dependence of mechanical losses, β and γ relaxation maxima are found below the glass transition temperature with activation energies of Eβ = 0.30 ± 0.05 eV and Eγ = 0.18 ± 0.04 eV, respectively. The first maximum is associated with the vibrations of the defective oxygen atoms of the epoxy groups of the polymer network, and the second maximum is attributed to the vibrations of the lateral OH groups of the main polymer network. The internal friction of the epoxy polymer in the region of α relaxation process has been studied. In this region, two segments with an intersection point at the glass transition temperature are seen in the temperature dependence of the internal friction in coordinates lnQ−1 vs. 1/T. The high temperature segment of the internal friction background is used to estimate the energies of migration and formation of vacancy-like defects in the amorphous matrix of glass reinforced plastics, which are associated with delocalized oxygen and equal to Em = 0.72 ± 0.05 eV and Ev = 1.41 ± 0.06 eV, respectively. [ABSTRACT FROM AUTHOR]

The effect of oxygen and water vapor in a sputtering chamber during the deposition of thin-film (Co40Fe40B20)x(LiNbO3)100 –x nanocomposites on the electrical properties of the heterogenous system is investigated. It is found that the resistivity of (Co40Fe40B20)x(LiNbO3)100 –x nanocomposites increases significantly with the partial pressure of reactive gases (oxygen and water vapor). A noticeable shift of the percolation threshold towards higher values of the metal phase volume concentration, which is observed in the plane of the film and in the perpendicular direction during the synthesis of composites with the addition of reactive gases, is attributed to the increase in the volume concentration of the dielectric phase. It is found that the percolation threshold for the measurements in the geometry perpendicular to the plane of the film is characterized by a much lower concentration of the Co40Fe40B20 alloy atoms than that for the measurements in the plane of the film, which is associated with an elongated shape of granules in the film growth direction and the effects of Coulomb blockade suppression by a high transverse electric field. [ABSTRACT FROM AUTHOR]

An investigation is performed of the thermal stability and phase transformations of thin-film heterogeneous [(Co40Fe40B20)34(SiO2)66/ZnO/In2O3]85 multilayers obtained via ion beam sputtering. The system contains 85 layers, each consisting of a (Co40Fe40B20)34(SiO2)66 composite layer and ZnO and In2O3 semiconductor spacers. The sample structure in the initial state and after heat treatment is studied by means of X-ray diffraction. It is shown that the samples are stable at temperatures of up to 500°С. Zn2SiO4, InBO3, CoFe, and In2O3 phases form during annealing. [ABSTRACT FROM AUTHOR]

We have studied the structure and electrical properties of thin films based on the In2O3 semiconductor and carbon, grown by atomic layer deposition using ion-beam sputtering. The structure of the resultant materials, formed during layer-by-layer growth of island layers, is made up of nanocrystalline In2O3 granules distributed at random over amorphous carbon. The electrical transport properties of the In2O3/C thin films depend on their thickness. In the temperature range 80–300 K, the dominant electrical transport mechanism in the In2O3/C thin films of thickness h < 70 nm sequentially changes from variable range hopping between localized states in a narrow energy band near the Fermi level (between 80 and 120 K) to nearest neighbor hopping (between 120 and 250 K) and then to variable range hopping between localized states in the conduction band tail (between 250 and 300 K). The films of thickness h > 70 nm undergo a change from conduction associated with strong carrier localization to that due to the presence of percolation clusters formed by In2O3 nanocrystals, which shows up as a linear temperature dependence of conductivity, with a negative temperature coefficient. [ABSTRACT FROM AUTHOR]

(ZnO/SiO2)25 thin-film multilayers consisting of nanocrystalline ZnO layers and amorphous SiO2 spacers with a bilayer thickness from 6 to 10 nm are synthesized in a single deposition process. An analysis of the temperature dependences of the electrical resistivity of (ZnO/SiO2)25 thin films shows that, in the temperature range of 77–300 K, the dominant conductivity mechanism successively changes from hopping conductivity with a variable hopping length in a narrow energy band near the Fermi level at temperatures of 77–250 K to thermally activated impurity conductivity around room temperature. Using the obtained temperature dependences of the electrical resistivity, the effective density of localized states at the Fermi level and the activation energy of impurity levels are estimated. The effect of heat treatment on the structure and electrical properties of the synthesized films is examined. It is established that in (ZnO/SiO2)25 thin-film systems at temperatures of 580–600°C, the ZnO and SiO2 layers chemically interact, which is accompanied by destruction of the multilayer structure and formation of the Zn2SiO4 compound with a tetragonal structure (sp. gr. I-42d). [ABSTRACT FROM AUTHOR]

Multilayered [(Co40Fe40B20)34(SiO2)66/ZnO]112, [(Co40Fe40B20)34(SiO2)66/SnO2]32, and [(Co40Fe40B20)34(SiO2)66/In2O3]92 films with layers 1 nm thick are obtained via the ion-beam sputtering of two targets onto a rotating substrate. Their phase transformations are studied during the thermal treatment of films. Compounds with boron form in films with ZnO and In2O3 buffer layers (Co2FeO2(BO3) and InBO3, respectively). The composition of these compounds is found to depend on the semiconductor that is used and the ratio of layer thickness. [ABSTRACT FROM AUTHOR]

The structure and electrical properties of In2O3 and SnO2 oxide semiconductors and heterostructures based on them has been experimentally investigated. The films were prepared by the method of layer-by-layer deposition using the ion-beam sputtering. The transition from the two-phase film of amorphous SnO2 and In2O3 islands, formed during the layer-by-layer deposition, to a multilayer structure consisting of the amorphous SnO2 and In2O3 continuous layers occurs with an increase in the bilayer thickness. The electrophysical properties of the (SnO2/In2O3)69 heterostructures are determined by the transition from the random distribution of SnO2 and In2O3 amorphous phases to a multilayer structure and the temperature range of measurement. For all studied systems, a consistent change in the prevailing mechanism of conductivity is observed at temperatures from 77 to 300 K. In (SnO2/In2O3)69 thin films with a bilayer thickness hbl < 2.5 nm, change of the prevailing conduction mechanism takes place according to the next sequence: variable range hopping conduction over localized states near the Fermi level, hopping conduction over the nearest neighbors and hopping transfer of carriers excited into localized states near the band edges at temperatures close to room temperature. [ABSTRACT FROM AUTHOR]

Abstract—The magnetostatic and magnetodynamic properties of laminated materials based on glass-reinforced plastic laminate coated with magnetic (Co40Fe40B20)60(SiO2)40 nanocomposite are studied. The modified magnetic composite structural materials based on glass fiber are characterized by hysteresis with a low coercivity and magnetic shape anisotropy related to fiber geometry. No significant absorption of electromagnetic radiation was observed in the range of frequencies of natural ferromagnetic resonance, except for the bulk composite sample, where minor peaks at 3 and 5 GHz were detected. In the variation in the coefficient of electromagnetic radiation transfer versus frequency curves, the signal intensity is substantially attenuated at 6–12 GHz owing to dielectric loss in the composite film. [ABSTRACT FROM AUTHOR]

The temperature and amplitude dependences of internal friction in hybrid composites consisting of unidirectional carbon fibers and glass tissues in a T-107 molten epoxy matrix have been studied. From the high-frequency portion of the internal friction background with regard to its low-frequency one, the energy of formation and migration of vacancy-like defects in an amorphous matrix of glass fiber- and carbon fiber-reinforced composites has been estimated. [ABSTRACT FROM AUTHOR]

Multilayer films (In2O3/SnO2)69 are obtained via ion-beam sputtering. The effect vacuum heat treatment in the range of room temperature to 600°C has on the structure and electrical properties is studied. It is found that the structures obtained with different thicknesses of the In2O3/SnO2 bilayer are stable up to a heat treatment temperature of 400°С. Raising the temperature to 600°C alters the sign of the coefficient of temperature resistance from negative to positive. [ABSTRACT FROM AUTHOR]

Results are presented from studying the magnetic resonance properties of metal–dielectric (CoFeB + SiO2) and metal–carbon (CoFeB + C) composite films. The effect the concentrations of the magnetic metal, dielectric, and carbon phases of the composite films on the characteristics of ferromagnetic resonance is analyzed. [ABSTRACT FROM AUTHOR]

Thin indium oxide films and In-Y-O films containing 0.7 to 3.6 at % Y have been grown by ionbeam sputtering of an indium target and a composite (indium + weighed amounts of yttrium) target in a mixture of argon and oxygen. The thin indium oxide films have a cubic crystal structure (sp. gr. Ia3¯). The incorporation of yttrium atoms into indium oxide leads to the formation of an amorphous structure in the as-grown films and an increase in their room-temperature electrical resistance by several orders of magnitude. Lowtemperature electrical resistance data indicate a change in conduction mechanism. High-temperature heat treatment of the thin In-Y-O films leads to the crystallization of their amorphous structure and an increase in their electrical resistance. [ABSTRACT FROM AUTHOR]

Abstract: Thin Zr-stabilized SnO2 films are fabricated by ion-beam reactive sputtering. The amorphous thin-film SnO2 samples with various Zr concentrations are synthesized in a single production process. The influence of heat treatment on the structure and electrical properties of the synthesized films is studied. The onset of crystallization in thin-film Sn-Zr-O systems is observed at 673 and 773 K, which is accompanied by the appearance of metastable phases. Being heated to 873 K, these phases are transformed into Sn + Sn2O3. It is found that the electrotransfer the film crystallization at temperatures close to room temperature is thermally activated with an activation energy of ~0.78 eV. Tin-oxide films doped with Zr from 0.6 to 3.9 at % manifest the property of hydrogen-gas sensitivity after crystallization. [ABSTRACT FROM AUTHOR]

The current‒voltage characteristics of the metal/nanocomposite (NC)/metal structures based on (Co41Fe39B20)x(LiNbO3)100-x NCs 2.4 and 3 μm thick are investigated in the fields of up to ~104 V/cm. The structures are synthesized via ion-beam sputtering of a composite target, in which NCs of different composition are formed in the single cycle at x = 5‒48 at %. The memristive effect (ME) manifesting itself during resistive switching of structures and the storage of incipient states has been detected at x ≈ 10 at %. It is ascertained that the ME depends weakly on used metal (Cu or Cr) contacts and the NC layer thickness, the number of switching cycles (without degradation) exceeds 105, and the ratio between the resistances of high- and low-resistance states, i.e., the Roff/Ron ratio, reaches approximately 65. The detected ME is explained by the fact that oxygen vacancies substantially affect the tunneling conductance of metal-granule chains determining the electric resistance of structures below the percolation threshold. [ABSTRACT FROM AUTHOR]

The properties of (CoFeB)x(LiNbOy)100-x nanocomposite films with a ferromagnetic alloy content x = 6-48 at % are comprehensively studied. The films are shown to consist of ensembles of CoFe granules 2-4 nm in size, which are strongly elongated (up to 10-15 nm) in the nanocomposite growth direction and are located in an LiNbOy matrix with a high content of Fe2+ and Co2+ magnetic ions (up to 3 × 1022 cm-3). At T ≤ 25 K, a paramagnetic component of the magnetization of nanocomposites is detected along with a ferromagnetic component, and the contribution of the former component is threefold that of the latter. A hysteresis of the magnetization is observed below the percolation threshold up to x ≈ 33 at %, which indicates the appearance of a superferromagnetic order in the nanocomposites. The temperature dependence of the electrical conductivity of the nanocomposites in the range T ≈ 10-200 K on the metallic side of the metal-insulator transition (44 at % < x < 48 at %) is described by a logarithmic law σ(T) ∝ lnT. This law changes into the law of “1/2” at x ≤ 40 at %. The tunneling anomalous Hall effect is strongly suppressed and the longitudinal conductivity turns out to be lower than in a (CoFeB)x(AlOy)100-x composite material by an order of magnitude. The capacitor structures based on (CoFeB)x(LiNbOy)100-x films exhibit resistive switching effects. They are related to (i) the formation of isolated chains of elongated granules and an anomalously strong decrease in the resistance in fields E > 104 V/cm because of the suppression of Coulomb blockage effects and the generation of oxygen vacancies VO and (ii) the injection (or extraction) of VO vacancies (depending on the sign of voltage) into a strongly oxidized layer in the nanocomposites, which is located near an electrode of the structure and controls its resistance. The number of stable resistive switchings exceeds 105 at a resistance ratio Roff/Ron ~ 50. [ABSTRACT FROM AUTHOR]

This work presents the results of research on mechanical properties of hybrid polymeric composite materials (PCM) with different percentage of carbon filler FormosaTC-35 (12K) and glass filler T-10-14 in epoxy matrix T-107. It was established that carbon-glass plastics are more preferable with respect to mechanical properties for application in constructions which work in bending. [ABSTRACT FROM AUTHOR]

The electrical properties and magnetoresistance of (Co 41Fe 39B 20) x(CaF 2) 100 − x composite are investigated. The principal mechanisms of electric charge transfer at low temperatures are determined. The effective density of localized states at the Fermi level and the average number of localized states between adjacent granules at various concentrations of the metal phase are estimated. [ABSTRACT FROM AUTHOR]

The effect of annealing on the structure and microwave magnetic properties of composite single-layer and multilayer films is investigated. It is found that as the threshold annealing temperature is attained, the width of the FMR line increases abruptly, depending on the concentration ratio of metallic alloy and dielectric. It is shown that the FMR line broadening is also associated with the occurrence of and increase in high-frequency modes of absorption. The surfaces of annealed and unannealed films are investigated at various concentrations of metallic alloys and dielectrics using an atomic force microscope. The strong change in the magnetic characteristics after film annealing is associated with a change in surface roughness and inhomogeneity, and in the size distribution of nano- and submicron formations and their spacing. [ABSTRACT FROM AUTHOR]

New heterogeneous multilayer composite-composite structures are obtained. Layers of the composite deposited in argon atmosphere alternate with layers of the composite deposited in argon atmosphere with the addition of oxygen or nitrogen. The layer thickness is several nanometers. The effect of the structure and composition on the magnetic properties of a heterogeneous system is investigated. [ABSTRACT FROM AUTHOR]

The magnetoelectric (ME) effect in two- and three-layered composites made up of polarized ceramic plates of lead zirconate-titanate PbZr0.53Ti0.47O3 (PZT) and manganese-zinc ferrite Mn0.4Zn0.6Fe2O4 (MZF) has been studied. Dependences of the transverse ME voltage coefficient (α31) on the magnetostrictive layer thickness and the magnetic field intensity and frequency have been established. The mechanical coupling coefficient of the composite plates has been estimated. Results obtained for two-layered PZT-MZF structures have been analyzed using the method of efficient medium parameters. [ABSTRACT FROM AUTHOR]

The magnetoelectric (ME) effect in two- and three-layered composites made up of polarized ceramic plates of lead zirconate-titanate PbZr0.53Ti0.47O3 (PZT) and manganese-zinc ferrite Mn0.4Zn0.6Fe2O4 (MZF) has been studied. Dependences of the transverse ME voltage coefficient (α31) on the magnetostrictive layer thickness and the magnetic field intensity and frequency have been established. The mechanical coupling coefficient of the composite plates has been estimated. Results obtained for two-layered PZT-MZF structures have been analyzed using the method of efficient medium parameters. [ABSTRACT FROM AUTHOR]

Nanocrystallization in amorphous Al83Ni10La7 and Al83.5Ni9.5La5.6Si1.4 alloys during heat treatment and flash lamp processing has been studied using X-ray diffraction, transmission electron microscopy, scanning calorimetry, and internal friction, modulus of elasticity, and microhardness measurements. The results demonstrate that thermal annealing and flash lamp processing have identical effects on the formation of a nanocrystalline structure in the amorphous alloys and their phase transformations. [ABSTRACT FROM AUTHOR]

We have studied the elastic and inelastic properties of composite materials of the Co x(PZT)1 − x system ( x = 0.23–0.79) possessing a nonequilibrium nanogranular structure with an average grain size of ∼3 nm. The results of mechanical tests performed in a temperature range of 300–900 K revealed a significant increase in the level of mechanical losses ( Q−1) above 750 K, which is caused by the thermoactivated migration of point defects. An additional heat treatment leads to grain coarsening and the appearance of a ferroelectric state in the dielectric matrix. The temperature dependences of Q−1 in annealed samples exhibit two maxima, one of which is due to the interaction of domain boundaries with lattice defects and the other is related to the motion of interfaces in the region of the ferroelectric phase transition. [ABSTRACT FROM AUTHOR]

The elastic (Young’s modulus) and inelastic (internal friction) properties of amorphous (Co45Fe45Zr10) x (Al2O3)100 − x nanocomposites with various relative contents of the metallic and dielectric phases have been studied. In the region of low temperatures, the composites exhibit a peak of the internal friction (at ∼240 K), the intensity of which increases with the content of the metallic phase. For compositions above the percolation threshold, the temperature dependence of the internal friction exhibits exponential growth above 300°C, which is related to the migration of vacancy-like defects in the amorphous structure of the metallic phase. [ABSTRACT FROM AUTHOR]

The field dependences of the thermopower of composites with Co and Co45Fe45Zr10 nanoparticles in the Al2O n insulator matrix are studied in magnetic fields up to 10 kOe at room temperature with compositions up to the percolation threshold (i.e., in the region where tunnel conductivity takes place). In composites obtained in argon, negative magnetothermopower (i.e., a decrease in the thermopower in strong magnetic fields) is observed, while positive magnetothermopower is observed in composites obtained in the atmosphere of argon and oxygen. It is shown that the theory developed for tunnel magnetothermopower in nanocomposites makes it possible to explain the results on a qualitative level in the case when the local density of electron states at the surface of nanoparticles depends on the sputtering conditions. Nanocomposites CoFeZr x (Al2O n )100− x ) obtained in argon and nitrogen display a strong asymmetry of magnetothermopower relative to the magnetic field direction; this anisotropy is associated with anisotropy of these nanostructures. [ABSTRACT FROM AUTHOR]

Magnetostructural methods are applied to determine the exchange bond percolation limit in (Co41Fe39B20)x(SiO2)1− x nanocomposites ( x c = 0.30 ± 0.02), which separates the phase plane along the metal concentration axis into a superparamagnetic region and a ferromagnetic region. It is shown that, with respect to the singularities of the magnetization up to the magnetization saturation curves, the ferromagnetic region is further subdivided into three regions differing in the character of the spatial propagation of the magnetization ripples or in the magnetic correlation function characteristics. The fractal dimension of the nanocomposite magnetic microstructure near the percolation threshold is determined. [ABSTRACT FROM AUTHOR]

Magnetic and magnetotransport properties of multilayered nanostructures Co0.45Fe0.45Zr0.1/ a-Si obtained by ion-beam sputtering are investigated. The temperature dependence of the resistance obeys a law of the form R xx ∝-log T, which is typical of metal-insulator nanocomposites on the metal side of the percolation transition. The magnetoresistance anisotropy effect, as well as the planar Hall effect, is observed for the first time for this type of nanocomposites in the vicinity of the percolation transition. The correlation of these two effects with the transverse (between Hall probes) magnetoresistive effect, which may reach 6–9%, is revealed. A weak negative magnetoresistance of the order of 0.15%, which is observed for subnanometer amorphous silicon layer thicknesses, is attributed to spin-dependent electron transitions between adjacent ferromagnetic layers in the case when the exchange interaction between these layers is of the antiferromagnetic type. [ABSTRACT FROM AUTHOR]

The processes occurring in amorphous Fe-P-Mn-V alloys at elevated temperatures, up to the crystallization temperature, are investigated by internal friction measurements and x-ray diffraction analysis. The results are used to evaluate the activation energy of defect migration and the particle size of the crystalline phases precipitating in the alloys during annealing. It is shown that increasing the vanadium content of amorphous Fe-P-Mn-V alloys increases the energy of defect migration and reduces the particle size of the precipitating phases. [ABSTRACT FROM AUTHOR]

Magnetic, optical, and magnetooptical (MO) properties of (Co45Fe45Zr10)x(SiO2)100 – x and (Co41Fe39B20)x(SiO2)100 – x granular nanocomposites of the amorphous ferromagnetic metal–insulator type were studied in a broad range of the magnetic component concentrations x. The MO response of nanocomposites increases in the vicinity of the percolation transition. Using the experimentally determined values of optical constants and the equatorial Kerr effect, the diagonal and nondiagonal components of the permittivity tensor of nanocomposites were calculated for the first time. The nondiagonal components of this tensor are nonlinear functions of x, the most pronounced variations being observed near the percolation threshold. Experimental data on the MO effect and the permittivity tensor were theoretically modeled within the framework of the effective medium approximation and the Maxwell–Garnett approximation. The most adequate description was obtained with the symmetrized Maxwell–Garnett approximation, which provides for a good (semiquantitative) agreement between theory and experiment under certain assumptions about the microstructure of nanocomposites. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Abstract-The magnetorefractive effect in ferromagnetic metal-insulator granular nanostructures (CoFeZr)-SiO[SUBn], Co-Al-O, FeSiO[SUBn], and (CoFe)-(Mg-F) is investigated in the infrared spectral region in a wavelength range from 5 to 20 μm. The magnitude of the effect varies from 0.1 to 1.5% for different nanocomposites and strongly depends on the frequency of light and magnetoresistance. It is shown that the reflection coefficient changes in a magnetic field not only due to the magnetorefractive effect, but also due to the even magnetooptical effect. Simple relations describing this effect are given for the case when the reflection from the substrate is insignificant and in the case of a three-layer (insulator-film-substrate) system. The expression for the frequency dependence of the magnetorefractive effect in nanocomposites is derived and its features in the case of high-frequency spin-dependent tunneling are analyzed. [ABSTRACT FROM AUTHOR]

The effect of pulsed photon annealing with energy densities from 1.4 to 42 J/cm² for various lengths of time on the structure of the amorphous alloy Fe79P14.2Si4.4Mn2.2V0.2 was studied by x-ray diffraction, differential scanning calorimetry, and transmission electron microscopy. The results demonstrate that short-term irradiation with low energy densities leads to surface relaxation of the amorphous alloy, increases the strength of the surface layer, and reduces the internal-friction peak. Longer term photon annealing leads to crystallization of the alloy throughout the sample thickness. [ABSTRACT FROM AUTHOR]

The technique of X-ray reflectometry used for studying the sizes of metallic and dielectric inclusions in nanocomposite films (Fe45Co45Zr10) · (Al2O3)100− x depending on their composition is described. The size of isolated metallic inclusions increases with an increase in metallic phase concentration and reaches its maximum in the region of the percolation threshold. Above this threshold, metallic inclusions merge, thus forming a matrix with dielectric inclusions. [ABSTRACT FROM AUTHOR]

The electrical properties of amorphous Co0.45Fe0.45Zr0.1/a-Si multilayer structures have been studied. It is established that the regime of inelastic resonance tunneling via localized states near the Fermi level is realized in these structures in the temperature interval from 150–220 K. This regime is preceded by variable-range hopping conductance and is followed by hopping via nearest-neighbor localized states. [ABSTRACT FROM AUTHOR]

Amorphous films of tin oxide doped with yttrium were obtained by ion beam sputter deposition. After crystallization, the films acquired a nanocrystalline structure. The introduction of yttrium leads to an increase in the crystallization temperature of tin oxide. The electric conductivity of films containing yttrium in excess of 1 at. % is highly sensitive to hydrogen. Nanocrystalline films of tin oxide doped with yttrium may serve as hydrogen-sensitive media. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

A new percolation situation has been found in metal-dielectric nanocomposites containing ferromagnetic components. For a certain concentration of metal atoms, the vectors of spontaneous magnetization of individual nanoparticles exhibit a correlated behavior. As a result, a structure containing a very large number of ferromagnetic nanoparticles shows magnetization reversal in a macroscopic nanocomposite volume in a single giant Barkhausen jump. [ABSTRACT FROM AUTHOR]