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Electronic properties of thin-film granulated nanocomposites Cox(LiNbO3)100-x, where x = 12-83 at.%, have been studied. The analysis of temperature dependences of a conductivity for compositions having Co content lower than the percolation threshold x = 58 at. % has revealed that in the low temperature region (80-190 K) a Mott's type variable range hopping conduction is observed and in the region of 190-290 K the electronic transport is due to inelastic resonant tunneling of electrons through localized states, which are located in amorphous dielectric layer between conducting isolated clusters. It is shown that the average number of localized states in dielectric matrix decreases as Co content in composites is increased. [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 electrical, magnetic and magnetoresistive properties of new Cox(LiNbO3)100- x composites have been investigated in a wide concentration region (12 at.% ≤ x ≤ 83 at.%) at room temperature. The composites resistivity non-smoothly decreases from 10-4 Ohm · m to 1 Ohm · m with change of the Co concentration from 12 at.% to 83 at.%. The sharp reduction of the resistivity at 850–870 K was observed in all studied samples when they are being heated. The composites in whole studied concentration range exhibit negative magnetoresistance as well as magnetic hysteresis with quite large coercivity (160–415 Oe, depending on a concentration). [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]