Browsing by Author "Klyukanov, Alexandr"

Now showing 1 - 7 of 7

Hartree-fock Semiconductor Bloch Equations and charge density correlations [Articol]
(2002) Klyukanov, Alexandr; Loiko, Natalia; Babushkin, Ihar; Gurau, Virginia
Generalized Semiconducor Bloch Equations are derived with using the fluctuation-dissipation theorem. Four op- erator expectation values like density-density correlators are calculated with account of coherent memory effects. Interactionswith mixed plasmon-phonons modes and excitonic effects are taken into account. Comparison with different other theoretical approaches is provided. Numerical calculations of the spontaneous radiationproduced by interband multiplasmon recombination of electron-hole pairs are fulfilled in dependence on the temperatureand plasmaconcentration. It is shown that the intensity maximum of spontaneous radiationshifted to the region of the first LO-phonon satellite with increasing of concentration in accordance with experiments [19,21].
Hysteresis and bistability in the I-V characteristics of P-N junctions [Articol]
(CEP USM, 2013-09-26) Klyukanov, Alexandr; Scurtu, Roman
Many-body correlations in the kinetic theory of solids [Articol]
(2009) Klyukanov, Alexandr
Multiquantum integral kinetic equations for the micropolarization and longitudinal di- electric function are derived with account of pair correlations. The Heisenberg equation of motion and fluctuation-dissipation theorem has been used to calculate a micropolarization. It has been shown that kinetic equation for a micropolarization may be represented as power series in fluctuations of the instantaneous plasma field near the mean field. Direct Coulomb pair correlations have been evaluated explicitly by means of fluctuation-dissipation theorem. The kinetic motion equation with regard for pair correlations has been used to derive a multi- quantum integral equation for the complex order parameter kΔ in a superconductor.
Microscopic fermi-liquid approach to the resonant effects of spin-orbit interaction in solids [Articol]
(CEP USM, 2017) Klyukanov, Alexandr; Nika, Denis
Kondo effect, saturation magnetization and heat capacity of ferromagnetic are calculated from the first principles in the spirit of Landau’s Fermi-liquid theory. Temperature dependence of resistivity of metal with magnetic impurity is obtained in a good agreement with existing experimental data. Resistance curves demonstrate a minimum due to the resonance character of the interaction between spins of the localized and conduction electrons. It has been demonstrated that both temperature dependence of magnetic momentum and internal energy of ferromagnetic are in a good agreement with those predicted by the Heisenberg’s model.
Multiplasmon laser gain spectra of quantum wells [Articol]
(2005) Klyukanov, Alexandr; Gurau, Virginia
Results of computer simulations concerning gain spectra of In0.05Ga0.95As quantum wells are presented. A novel multi-plasmon concept of a light absorption and laser gain of low- dimensional structures is comprehensively discussed. A generalized theory of multi-plasmon optical transitions in direct gap quantum wells is developed using the cumulant expansion method and fluctuation-dissipation theorem. Multi-quantum LO-phonon-plasmon optical transitions are investigated with account on coherent memory effects in quantum wells. It is shown that a red shift of the absorption edge can be caused not only by the well-known mechanism of band gap shrinkage but also by multi-plasmon transitions. The comparison with other theories and experimental data measured in In0.05Ga0.95As quantum wells is given.
Multiplasmon radiation line replicas of bound excitons in single ZnSe crystals [Articol]
(2006) Klyukanov, Alexandr; Sushkevici, Konstantin; Chyukichev, M.; Awawdeh, Adnan; Gurau, Virginia; Catanoi, A.
The cathode-luminescence of ZnSe single crystals, grown from vapour phase and heat treated in Bi melts [ZnSe(Bi)] at 1200 K for 120h, and also in Bi melts doped by Al [ZnSe(Bi, Al)] were investigated at 4.2 K. The LO-phonon replicas of free excitons emission line dominate in cathode-luminescence spectra of the samples heat treated in Bi followed by water quenching. The lines of bound excitons series, nLOI ds −, 1 , were observed in the emission of all samples, including the original ones. It was found that plasmon replicas are not proper only for nLOI s −1 lines, but, also, for nLOI d −1 lines. The weak exciton-plasmon coupling is manifested in one plasmon Stokes side band shoulders of nLOI d −1 lines. It is developed the theory of bound excitons multi-quantum optical transitions with participation of mixed plasmon-phonon oscillation modes. This theory allows for the calculation of the emission spectra form–function, without using any model. The theoretical spectra are in agreement with the experimental data.
Multiquantum kinetic equation and charge density fluctuations [Articol]
(2009) Klyukanov, Alexandr
A multiquantum integral equation for the longitudinal dielectric function is derived accounting for of pair correlations. The Heisenberg equation of motion and fluctuation-dissipation theorem has been used to calculate a microscopic polarization. It has been shown that a kinetic equation for a polarization may be represented as a power series in fluctuations of instantaneous field near the mean field. Direct Coulomb pair correlations have been evaluated explicitly by means of a fluctuation-dissipation theorem. The energy and the effective mass of an electron of momentum k in the degenerate electron system and damping of one-electron states have been computed at rs ≥ 1.