Magnetization distribution in submicrometer iron-nickel antidot arrays patterned by a focused ion beam

Antidots of size 0.5 μm are prepared by patterning iron-nickel films with a focused ion beam. The magnetization distribution in antidot arrays is examined with Lorentz transmission electron microscopy. It is shown that one side of the array makes an angle of about 20° with the easy magnetic axis of the film. Magnetization reversal in the direction close to the easy magnetic axis starts with domain nucleation at the antidot edges that are perpendicular to the applied field and adjacent to the unpatterned region of the film, and propagates as the domain walls move. Magnetization reversal in the direction close to the hard magnetic axis starts with magnetization rotation outside the patterned region at the antidot edges and propagates as the domain walls execute a complicated motion. It is demonstrated that some areas between the edges of adjacent antidots can carry information bits. Results obtained are explained in terms of competition between the demagnetizing energy, energy of internal anisotropy, and misorientation effect. The feasibility of such structures as high-density storage elements is discussed.     

Investigation on the adhesion of polymer particles to the surface of a semiconductor

In this work the role of electrostatic forces in the adhesion of particles of dielectrics to a solid surface was studied. The experiment consisted in measuring simultaneously the force of adhesion and the charges of the electric double layer arising upon contact. The measurements were made with specially developed units—a pneumatic adhesiometer and a charge-spectrometer. The objects of study were polymer powders used in electrography, whose adhesion to thin layers of selenium samples were varied by varying the illumination and were estimated by their volume resistance in the dark and in the light. The shift in the Fermi level of the selenium caused by the change in the output work is accompanied by a change in adhesion of the particles. Experiments on the separation of polymer particles and films from selenium surface on illumination revealed spectral dependence of adhesion. In accordance with the electronic theory of adhesion, the effects observed may be attributed to the change in charge density of the electric double layer.     

Influence of adhesion on the sliding and rolling friction

Yet in 1934, one of the authors had developed the molecular friction theory explaining the external friction by dissipation of energy on the molecular unevenness of the bodies in friction. This theory distinctly determines the role of adhesion in the processes of the external sliding friction. The adhesion forces are used in this theory only for explaining deviation from the Amonton's law expressing the proportionality of the friction force to the normal load.

The rolling friction process (in the absence of deformations) represents a process of formation and breakage of adhesion bonds. Using the electron theory as the basis, the mechanism of influence of the electrostatic component of adhesion on the rolling friction is considered, the electrostatic component being attributable to the formation of a double electric layer when solids are in friction, and when its plates are separated as the contact is broken.     

A modification of the successive projections algorithm for spectral variable selection in the presence of unknown interferents

This work proposes a modification to the successive projections algorithm (SPA) aimed at selecting spectral variables for multiple linear regression (MLR) in the presence of unknown interferents not included in the calibration data set. The modified algorithm favours the selection of variables in which the effect of the interferent is less pronounced. The proposed procedure can be regarded as an adaptive modelling technique, because the spectral features of the samples to be analyzed are considered in the variable selection process. The advantages of this new approach are demonstrated in two analytical problems, namely (1) ultraviolet–visible spectrometric determination of tartrazine, allure red and sunset yellow in aqueous solutions under the interference of erythrosine, and (2) near-infrared spectrometric determination of ethanol in gasoline under the interference of toluene. In these case studies, the performance of conventional MLR-SPA models is substantially degraded by the presence of the interferent. This problem is circumvented by applying the proposed Adaptive MLR-SPA approach, which results in prediction errors smaller than those obtained by three other multivariate calibration techniques, namely stepwise regression, full-spectrum partial-least-squares (PLS) and PLS with variables selected by a genetic algorithm. An inspection of the variable selection results reveals that the Adaptive approach successfully avoids spectral regions in which the interference is more intense.     

Characterization of III–V compounds by quasi-elastic electronic scattering of light

Quasi-elastic light scattering from individual electron single-particle excitations is observed experimentally and studied theoretically in n-GaAs and n-InP samples with nonparabolic dispersion of energy bands for a wide range of free-electron concentrations varying from ≈10⁸ to ≈10¹⁹ cm^-3. The results indicate that the scattering mechanisms associated with charge-, spin- and momentum-density fluctuations are represented by different light scattering line shapes and occur in different concentration ranges.     

Polariton enhancement of the Faraday magnetooptic effect

Enhancement of the Faraday magnetooptic effect by the excitation of surface polariton on an interface between an iron garnet and silver is observed. The main contribution to this effect is due to the rotation of the polarization of a surface polariton as the polariton propagates along the interface. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 5, 376–379 (10 September 1998)     

Mechanochemical synthesis of polymer π complexes on the newly formed surface of lithium fluoride

The possibility of the mechanochemical synthesis of polymer complexes on a newly formed surface of finely divided particles under conditions of combined vibrodispersion of LiF-PVC and LiF-maleic anhydride systems was established. Some optical, electric, and magnetic properties of the resulting polymer organic complexes are discussed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2730–2736, December, 1990.