Calculations of exchange interaction in impurity band of two-dimensional semiconductors with out of plane impurities

We calculate the singlet-triplet splitting for a couple of two-dimensional electrons in the potential of two positively charged impurities which are located out of plane. We consider different relations between vertical distances of impurities $h_1$ and $h_2$ and their lateral distance $R$. Such a system has never been studied in atomic physics but the methods, worked out for regular two-atomic molecules and helium atom, have been found to be useful. Analytical expressions for several different limiting configurations of impurities are obtained an interpolated formula for intermediate range of parameters is proposed. The $R$-dependence of the splitting is shown to become weaker with increasing $h_1,h_2$.Comment: 14 pages, RevTeX, 5 figures. Submitted to Phys Rev.

Influence of the annealing temperature on the ferroelectric properties of niobium-doped strontium–bismuth tantalate

Characteristics of ferroelectric thin films of nio-bium-doped strontium–bismuth tantalite (SBTN), which were deposited by magnetron sputtering on Pt/TiO2/SiO2/Si substrates, are investigated. To form the ferroelectric structure, deposited films were subjected to subsequent annealing at 700–800°C in an O2 atmosphere. The results of X-ray diffraction showed that the films immediately after the deposition have an amorphous structure. Annealing at 700–800°C results in the formation of the Aurivillius struc-ture. The dependences of permittivity, residual polariza-tion, and the coercitivity of SBTN films on the modes of subsequent annealing are established. Films with residual polarization 2Pr = 9.2 μC/cm2, coercitivity 2Ec = 157 kV/cm, and leakage current 10–6 A/cm2 are obtained at the annealing temperature of 800°C. The dielectric constant and loss tangent at fre-quency of 1.0 MHz were ε = 152 and tanδ = 0.06. The ferroelectric characteristics allow us to use the SBTN films in the capacitor cell of high density ferroelectric random-access non-volatile memory (FeRAM)

The Use of Computer Technologies in the Process of Physical Education of Student Young People.

В статье представлена разработанная авторами информационно -методическая система “Гармония тела”, раскрываются назначение и возможности модулей компьютерной программы. In the article the developed by authors informative- methodical system is presented “Harmo ny of body”, setting and p ossibilities of computer program units open up

Antiproton-Hydrogen annihilation at sub-kelvin temperatures

The main properties of the interaction of ultra low-energy antiprotons ($E\le10^{-6}$ a.u.) with atomic hydrogen are established. They include the elastic and inelastic cross sections and Protonium (Pn) formation spectrum. The inverse Auger process ($Pn+e \to H+\bar{p}$) is taken into account in the framework of an unitary coupled-channels model. The annihilation cross-section is found to be several times smaller than the predictions made by the black sphere absorption models. A family of $\bar{p}H$ nearthreshold metastable states is predicited. The dependence of Protonium formation probability on the position of such nearthreshold S-matrix singularities is analysed. An estimation for the $H\bar{H}$ annihilation cross section is obtained.Comment: latex.tar.gz file, 22 pages, 9 figure