Effect of dielectric environment on exciton spectrum of silicon quantum fibers
Effect of dielectric environment on exciton spectrum of silicon quantum fibers
M.G. Lisachenko, V.Yu. Timoshenko
The problem of an exciton in a silicon quantium fiber $2\div4$ nm in diameter with permittivity $\varepsilon_i$ on a medium with permittivity $\varepsilon_e$ has been solved numerically. It was found that, if $\varepsilon_e<\varepsilon_i$ the exciton radius was smaller and the binding energy higher than for $\varepsilon_e=\varepsilon_i$. Conversely, with $\varepsilon_e>\varepsilon_i$, the exciton radius increased, while the binding energy sharply decreased. This explains the experimental data on dielectric quenching of exciton luminescence of porous silicon.
Show AbstractDielectric relaxation m vinylidene fluoride/trifluorethylene copolymer doped with rhodamine 6G
Dielectric relaxation m vinylidene fluoride/trifluorethylene copolymer doped with rhodamine 6G
A.G. Chaplygin, I.A. Malyshkina, N.D. Gavrilova, K.A. Verkhovskaya
The authors have investigated the dynamic dielectric properties of a vinylidene fluoride/trifluorethylene copolymer (70 mol.% and 30 mo!.%, respectively) in the presence of 6G rhodamine polar dopant (0, 0.2, 0.6, 1, and 1.5 wt.%). The measurements were made by the bridge method in the 80-300 K temperature range at frequencies of from 20 Hz to 20 kHz. The dielectric constant was found to depend nonmonotonically on the concentration of the dopant that may be due to the polar nature of rhodamine 6G. It was found that the presence of the dopant and its concentration affect the mobility of chain segments in the amorphous phase and the conduction mechanism in the copolymer.
Show AbstractInfluence of s-d-scattering on quantum size effect in conductivity of ferromagnetic metal thin films
Influence of s-d-scattering on quantum size effect in conductivity of ferromagnetic metal thin films
A.V. Vedyayev, O.A. Kotel'nikova, N.G. Pugach
The conductivity of a thin metal film for the $s$-$d$-exchange model has been calculated in the context of Kubo's formalism using the Green function method. Due account is taken of the dependence of conduction electron scattering amplitude on the film thickness resulting from the quantum size effect, and the probability for $s$-electrons to be scattered into the split $d$-zone. Conductivity has been described by an oscillating function of the film thickness with periods that correspond to the Fermi momenta of $d$-electrons.
Show AbstractThe nature of spin-glass phase in semiconducting spin glasses of the $x$CuCr$_2$Se$_4$-$(1-x)$Cu$_{0,5}$Me$_{0,5}$Cr$_2$Se$_4$ (Me${}={}$In, Ga) system
The nature of spin-glass phase in semiconducting spin glasses of the $x$CuCr$_2$Se$_4$-$(1-x)$Cu$_{0,5}$Me$_{0,5}$Cr$_2$Se$_4$ (Me${}={}$In, Ga) system
A.I. Abramovich, L.I. Koroleva
The dependence of magnetoresistance $\Delta\rho/\rho$ on the square of magnetization $\sigma^2$ in strong magnetic fields has be studied for the $x$CuCr$_2$Se$_4$-$(1-x)$Cu$_{0,5}$Me$_{0,5}$Cr$_2$Se$_4$ (Me${}={}$In, Ga) system. Both in spin glasses and in the reciprocal spin glass, the slope of the $(\Delta\rho/\rho)(\sigma^2)$ dependences was shown to change at freezing temperature $T_f$ suggesting that at $T=T_f$, the spin system experienced substantial rearrangement, that is, underwent a thermodynamic phase transition. The spin-glass phase in the reciprocal spin glass was shown to consist of spins of separate Cr$^{3+}$ ions, whereas spin glasses contained not only these ions but also interacting ferromagnetic clusters.
Show AbstractNonequilibrium oscillating-type phase transformations in a Pd-Er alloy relaxing after saturation with hydrogen
Nonequilibrium oscillating-type phase transformations in a Pd-Er alloy relaxing after saturation with hydrogen
V.M. Avdyukhina, A.A. Katsnelson, G.P. Revkevich
Oscillating changes have been found in the volume content of phases and in the difference in erbium atoms density in these phases in a Pd-Er alloy following its saturation with hydrogen. A model has been suggested according to which this phenomenon is associated with the competition between the ascending and gradient diffusion processes in the nonequilibrium medium. The nonequilibrium character of the medium is due to the presence of hydrogen-enriched defect-metal complexes.
Show AbstractTransformation of ocean stratification structure resulting from underwater earthquake
Transformation of ocean stratification structure resulting from underwater earthquake
M.A. Nosov, S.N. Skachko
Turbulent energy and turbulent heat transfer balance equations are used for evaluating the possibility of vertical temperature profile transformation resulting from an underwater earthquake.
Show AbstractMethod of modeling potentials for Schr$\stackrel{..}{o}$dinger equation
Method of modeling potentials for Schr$\stackrel{..}{o}$dinger equation
V.N. Sidorenko
A method of modeling potentials is discussed for constructing the energy spectrum of the Schr$\stackrel{..}{o}$dinger equation in quasiclassical framework. The idea of the method consists in constructing a modeling potential, which is simpler than the original potential not necessarily being locally close to the latter, but with the same global structure of the spectrum.
Show AbstractSchr$\stackrel{..}{o}$dinger equation for an oscillator. A spectral problem
Schr$\stackrel{..}{o}$dinger equation for an oscillator. A spectral problem
A.S. Vshivtsev, V.A. Vshivtsev, A.V. Tatarintsev, A.R. Frenkin
A procedure for finding the spectrum of the one-dimensional Schr$\stackrel{..}{o}$dinger equation for a linear oscillator and a phase-shift oscillator has been suggested. The procedure is related to examination of the analytical properties of the Laplace images of wave functions.
Show AbstractExperimental investigations into the structure of polarized bremsstrahlung of relativistic electrons in polycrystalline aluminum
Experimental investigations into the structure of polarized bremsstrahlung of relativistic electrons in polycrystalline aluminum
S.V. Blazhevich$^1$, V.K. Grishin$^2$, O.S. Ishkhanov$^2$, N.N. Nasonov$^1$, V.P. Petukhov$^2$, V.I. Shvedunov$^2$
We have investigated experimentally the influence of collective effects on the structure of the polarized bremsstrahlung of relativistic electrons in a polycrystalline aluminum film. The experiment was conducted using an electron accelerator with electron energy of 2.4 Mev built at the Research Institute of Nuclear Physics attached to Moscow State University. The peaked structure of polarized bremsstrahlung observed for the first time agrees with the theoretical predictions.
Show AbstractViolation of the Mooij rule in ferromagnetic composites Co$_x$(CuO)$_{100-x}$ and Co$_x$(Al$_2$O$_3$)$_{100-x}$
Violation of the Mooij rule in ferromagnetic composites Co$_x$(CuO)$_{100-x}$ and Co$_x$(Al$_2$O$_3$)$_{100-x}$
A.B. Granovsky$^1$, V.A. Kovalev$^1$, H.R. Khan$^2$, V.N. Prudnikov$^1$, M.V. Prudnikova$^1$
It is demonstrated that the Mooij rule is violated for the composites Co$_x$(CuO)$_{100-x}$ and Co$_x$(Al$_2$O$_3$)$_{100-x}$ with $x>40$ (%), namely, the resistance of these systems does not tend to saturation, as their temperature increases and reaches $300\div7000$ μ$\Omega\cdot$cm, which is many imeslthe value of $\rho^*\approx150$ μ$\Omega\cdot$cm, with the temperature resistance coefficient remaining positive. The violation of the Mooij rule is associated with an important role played by intergranular contacts in the resistance growth.
Show Abstract