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Using wide-band (0.5-6.5 eV) spectroscopic ellipsometry we study ultrathin [Bi(0.6-2.5 nm)-FeNi(0.8,1.2 nm)]N multilayer films grown by rf sputtering deposition, where the FeNi layer has a nanoisland structure and its morphology and magnetic properties change with decreasing the nominal layer thickness. From the multilayer model simulations of the ellipsometric angles, Psi(omega) and Delta(omega), the complex (pseudo)dielectric function spectra of the Bi layer were extracted. The obtained results demonstrate that the Bi layer can possess the surface metallic conductivity, which is strongly affected by the morphology and magnetic properties of the nanoisland FeNi layer in the GMR-type Bi-FeNi multilayer structures., 6 pages, 4 figures

A study is performed of the effect the morphology of films consisting of silver nanoparticles chemically deposited on porous silicon films and monocrystalline silicon wafers with textured surfaces has on the conditions for observing plasmon resonance. It is shown that the investigated semiconductor structures can be used as sensors for complex organic molecules, and biological objects of micron and submicron size that produce the SERS effect.

We study the thermoelectric properties of island metal films on a dielectric substrate. Dependence of thermoelectric coefficient of metal films on their thickness with the dimensionless conductance g > 1 and g 1 was investigated. Also, the thermopower dependence of island metal structures with g 1 on the chemical composition of nanostructures was studied. We found that regardless of tunneling or Drude character of conductivity, the value of the thermoelectric coefficient in island metal films is determined by the properties of film metal element.

We study the magnetic anisotropy of multilayer nanostructures [Co–Al 2 O 3 ] N with fixed Co island layer thickness ( d ≈ 1 . 2 nm ) and varying Al 2 O 3 layer thickness. We use the Kerr effect to measure the magnetization hysteresis loops at different orientations of the magnetic field. We observed a unidirectional magnetic anisotropy in structures with small thicknesses of Al 2 O 3 layers ( d 1 . 4 nm ) when the exchange interaction between the Co layers is large. This anisotropy was oriented at 150° with respect to the easy axis of a continuous Co film. We believe that the unidirectional anisotropy can be caused by the super-vortex magnetization of the multilayer structure, while the unidirectional magnetization is caused by the projection of the super-vortex core on the sample plane.

We have studied the conductivity and permittivity of a series of nanoisland-type FeNi films with an effective thickness of up to 3.2 nm on different substrates. It has been observed that the quantity Re e changes its sign at effective thickness d * ≈ 1.5–1.8 nm, because of the metal–insulator transition. Analysis of the temperature dependences of the conductivity has confirmed the existence of the metal–insulator transition at the same thickness d *. It has been concluded that the introduced effective permittivity can serve as a characteristic of island metal systems.

Process of magnetization and magnetoresistance have been studied in nanoisland bilayer systems of FeNi-Co. Hysteresis loops show characteristic features (steps) most clearly observed in certain orientations of the sample in a magnetic field. To explain these features the concept of flat magnetic exchange spring has been introduced for nanoisland bilayers. It has been proposed that additional magnetoresistance can be the result of spin-dependent scattering of electrons in the area of flat magnetic exchange spring. Magnetoresistance studies of bilayer systems has shown that additional magnetoresistance occurs at the same magnetic fields as steps on hysteresis loops.

A new method is proposed that allows an integrated technology to be used for the synthesis of carbon planar structures with predetermined properties. The method is based on the avalanche annealing of amorphous short-period superlattices. The synthesized samples are investigated by Raman spectroscopy and photoluminescence. The possibility of synthesizing carbon layers with diamond-like, graphite-like, graphene, or other structures is demonstrated experimentally using the example of a C/SiC superlattice.

The Raman and photoluminescence spectra of short-period C/SiC superlattices produced by RF magnetron sputtering are investigated. The Raman data indicate that, in 35-period Sitall/Ni/[C/SiC] superlattices with the C and SiC effective thicknesses of 3.5 and 3 A, respectively, subjected to postgrowth avalanche annealing, the carbon layers assume the structure of multilayer graphene with 3–5 graphene sheets per superlattice period. A method for the fabrication of graphene-like carbon structures on the basis of short-period superlattices grown by RF sputtering is suggested and implemented.

The low-frequency effective permittivity of island metal films has been investigated as a function of the frequency of the electric field. It has been found that the low-frequency effective permittivity has a complex dependence on the measuring electric field frequency. It has been shown that, at the electric field frequency f = 1 kHz, the permittivity has a positive sign (e ≈ 108). With an increase in the electric field frequency, the permittivity decreases, and in the single-layer FeNi film with a thickness d = 8 A at a frequency f ≈ 10 kHz, it is equal to zero (e ≈ 0). With a further increase in the electric field frequency, the permittivity becomes negative and, at a frequency f = 100 kHz, reaches the value e ≈–108. It has been established that an increase in the effective permittivity of island metal films with a decrease in the electric field frequency is associated with the activation or tunneling processes in island films.

Results of measurements of the specific surface conductance of island metal films at different temperatures are presented. The study of conduction allowed us to establish processes, which determine the transfer of charge carriers in granular and island metal structures. These processes determine the excess charge carriers concentration in film and, on the other hand, characterize the transfer speed of excess charge carriers from one island to another (i.e. mobility). Moreover, these processes occur independently from each other.

We determine frequency dependences of coefficients of nonlinear conductance of island metal films (IMFs) and maxima of nonlinearity from the experimental data, when voltages of two frequencies are applied to IMFs of FeNi or Ti. We provide a theoretical description of the dispersion of the IMF nonlinear conductance. We investigate various schemes of measurements of the IMF nonlinear conductance. Our results can be used in optimizing the detection of the IMF nonlinear conductance, including IMFs used as protection labels against forgery of capital issues and products, in experiments on the generation of harmonics and in studies of nonlinear electrical properties of IMFs.

New magnetic structures such as multilayer systems of magnetic nanoislands being alternating layers of nanoislands of various magnets have been proposed. The electric, magnetic, and magnetooptical properties of the systems have been studied. The magnetoresistance of ∼2% related to the anisotropic effect has been revealed. In multilayer structures of magnetic nanoislands, a unidirectional axis of predominant magnetization has been found, which changes its orientation depending on the structure parameters. The magnetic field required to reorient the axis in the opposite direction has been estimated to be 2 kOe < HA < 20 kOe. The periodic multilayer structures of magnetic nanoislands are very sensitive to hyperweak magnetic fields (to 10−6 Oe).

The results of studies of magnetization processes of multilayer structures, consisting of periodically alternating island layers of various magnetic materials, are presented. The unidirectional axis of magnetization, which does not lead to exchange bias of hysteresis loops, is found in these structures. A vortex-like type of magnetization of island structures, when the vortex magnetization is distributed on set of nanoislands, is proposed. Preliminary simulations and experiments on the effects of vortex magnetic field on island systems have shown that proposed vortex-like state can be implemented in multilayer island systems and can influence their magnetic structure.

Statistically significant data indicating selective interaction of noradenaline and cAMP as well as of acetylcholine and cGMP were obtained in experiments on the microionophoretic bringing of cyclic purine nucleotides and mediator substances acetylcholine and noradrenaline to the rabbit cortical neurons. Studies on the relationships between cAMP and cGMP at the single unit level suggest their multilevel functional interaction with other systems of intracellular regulators.