arXiv subjects

V. D. Krevchik

Publications and source records attributed to V. D. Krevchik.

13 recordsLinked to original sources

arXiv2016

Phonon assisted resonant tunnelling and its phonons control

We observe a series of sharp resonant features in the tunnelling differential conductance of InAs quantum dots. We found that dissipative quantum tunnelling has a strong influence on the operation of nano-devices. Because of such tunnelling the current-voltage characteristics of tunnel contact created between atomic force microscope tip and a surface of InAs/GaAs quantum dots display many interesting peaks. We found that the number, position, and heights of these peaks are associated with the phonon modes involved. To describe the found effect we use a quasi-classical approximation. There the tunnelling current is related to a creation of a dilute instanton-anti-instanton gas. Our experimental data are well described with exactly solvable model where one charged particle is weakly interacting with two promoting phonon modes associated with external medium. We conclude that the characteristics of the tunnel nanoelectronic devices can thus be controlled by a proper choice of phonons existing in materials, which are involved.

cond-mat.mes-hall↗

arXiv2007

Nonlinear Dynamics of Infectious Diseases Transfer with Possible Applications for Tubercular Infection

In this paper, we model a nonlinear dynamics of infectious diseases transfer. Particularly, we study possible applications to tubercular infection in models with different profiles (peak values) of the population density dependence on spatial coordinates. Our approach is based on the well known method of instantons which has been used by the authors to describe kinetics of adiabatic chemical reactions as a function of the heat-bath temperature and other system parameters. In our approach, we use "social temperature" T as one of the controlling parameters. Increase of T leads to acceleration of the infectious diseases transfer. The "blockage" effect for the infectious diseases transfer has been demonstrated in the case when peak values (in the population density) are equal to one and under condition that the "social temperature" is low. Existence of such effect essentially depends from environment "activity" (social and prophylactic). Results of our modeling qualitatively meet the tuberculosis dynamic spread data in Penza region of Russia.

physics.med-ph↗

arXiv2007

Theory of Acoustic Emission for Micro-Cracks Appeared Under the Surface Layer Machining by Compressed Abrasive

One of the possible mechanisms for acoustic emission of growing micro-cracks under conditions of the material machining by com-pressed abrasive has been theoretically studied. Physical ground of this mechanism is the dislocation creep in the field of instant contact temperature on stage of micro-cutting with appearance of the wedge-shaped cavity. It has been shown that the energy density for radiated acoustic wave at the moment when the cavity is opened essentially depends on parameters of the material abrasive machining.

cond-mat.mtrl-sci↗

arXiv2006

Acoustic Emission of Growing Microcracks in Vibration-Loaded Material

We propose mechanism describing an acoustic emission by growing microcracks in the material under external cycled load. We use the theoretical approach based on Huygens principle for elastic solid con-tinuum with an account for dislocation creep in the zone of abrasive action. We show that the acoustic emission is anisotropic and its main direction depends not only on the effective length of microcrack but also on dynamics of dislocation structure and on diffusion processes in Kottrell zone which give rise to microcracks.

cond-mat.mtrl-sci↗

arXiv2005

Magneto-optics of multi-well quantum structures with D2- centres

The problem of electron binding states in field of two D0 centres in semiconductive quantum well (QW) in the presence of an external longitudinal magnetic field (along the QW growth axis) is studied within the framework of zero-range potential model. It is found that the magnetic field leads to a considerable change in positions of g- and u-terms, and to a stabilization of the D2- states in QW. It is shown that a form of impurity magneto-optical absorption spectrum essentially depends on the light polarization direction and on the spatial configuration of the D2- molecular ion in QW.

cond-mat.stat-mech↗

arXiv2005

Dissipative tunneling in structures with quantum dots and quantum molecules

The problem of tunneling control in systems "quantum dot - quantum well" (as well as "quantum dot - quantum dot" or quantum molecule) and "quantum dot - bulk contact" is studied as a quantum tunneling with dissipation process in the semiclassical (instanton) approximation. For these systems temperature and correlation between a quantum dot radius and a quantum well width (or another quantum dot radius) are considered to be control parameters. The condition for a single electron blockade is found in the limit of quantum dot. The criteria for an extreme tunneling current in quantum molecules are also presented. The tunnel probability for systems under investigation is analytically obtained as well.

cond-mat.stat-mech↗

arXiv2003

Magneto-optical properties of the quantum dot - impurity center systems synthesized in a transparent dielectric matrix

Magneto-optical absorption by the quantum dot (QD) with impurity center (IC or D(-)-center) complexes synthesized in a transparent dielectric matrix, with consideration of the QD size dispersion, is theoretically studied. Within the framework of effective mass approach, the analytical expression for the light impurity magneto-optical absorption coefficient for both the longitudinal and transversal polarizations with respect to the direction of external quantizing magnetic field is calculated.

cond-mat.mtrl-sci↗

arXiv2003

Two-dimensional tunnel bifurcations with dissipation

Two-particle tunneling in synchronous and asynchronous regimes is studied in the framework of dissipative quantum tunneling. We show that the use of the proposed model is justified by a comparison with realistic potential energy surfaces of porphyrin and experimental dependence of the reaction rate on temperature. The critical temperature T_c corresponding to a bifurcation of the underbarrier trajectory is determined. The effect of a heat bath local mode on the probability of two-dimensional tunneling transfer is also investigated. At certain values of the parameters, the degeneracy of antiparallel tunneling trajectories is important. Thus, four, six, twelve, etc., pairs of the trajectories should be taken into account (a cascade of bifurcations). For the parallel particle tunneling the bifurcation resembles phase transition of a first kind, while for the antiparallel transfer it behaves as second order phase transition. The proposed theory allows for the explanation of experimental data on quantum fluctuations in two-proton tunneling in porphyrins near the critical temperature.

cond-mat.soft↗

arXiv2003

Two-dimensional tunnel correlations with dissipation

Tunneling of two particles in synchronous and asynchronous regimes is studied in the framework of dissipative quantum tunneling. The critical temperature T_c corresponding to a bifurcation of the underbarrier trajectory is determined. The effect of a heat bath local mode on the probability of two-dimensional tunneling transfer is also investigated. At certain values of the parameters, the degeneracy of antiparallel tunneling trajectories is important. Thus, four, six, twelve, etc., pairs of the trajectories should be taken into account (a cascade of bifurcations). For the parallel particle tunneling the bifurcation resembles phase transition of a first kind, while for the antiparallel transfer it behaves as second order phase transition. The proposed theory allows for the explanation of experimental data on quantum fluctuations in two-proton tunneling in porphyrins near the critical temperature.

cond-mat.mes-hall↗

arXiv2003

Magneto-optics of quantum wires with D(-)-centers

The impurity magneto-optical absorption for the cases of longitudinal and transversal light polarization with respect to the quantum wire axis has been theoretically studied. Analytical expressions for the corresponding D(-)-centers photo-ionization cross sections under the action of longitudinal magnetic field have been obtained, and their spectral dependences for InSb quantum wires have been investigated.

cond-mat.str-el↗

arXiv2002

Photonic Drag Effect for One-Dimensional Electrons in a Longitudinal Magnetic Field with D(-)-Centers Participation

The impurity photonic drag effect (PDE), theory for semiconductive quantum wire (QW) in a longitudinal (along the quantum wire axis) magnetic field B, has been developed. The PDE is due to the photon longitudinal momentum transmission to localized electrons, under optical transitions from D(-)-states to QW hybrid-quantum states, if the QW is described by the parabolic confinement potential. The analytical expression for the drag current (DC) density has been obtained within the framework of zero-range potential model and in the effective mass approximation. The drag current spectral dependence has been investigated for various values of B and QW parameters, under electron scattering on the dotty-impurities system. The drag current spectral dependence is characterized by Zeeman doublet with a pronounced beak-type peak. This peak is related to electron optical transitions from D(-)-states to the states with the magnetic quantum number m=1. With an increase of the magnetic field B the beak-type peak is shifted to short-wave spectrum region, and the peak height considerably increases. We discuss the possibility of using of the one-dimensional drag current effect, in a longitudinal magnetic field, to develop a new type of laser radiation detectors.

cond-mat.str-el↗

arXiv2002

Quantum Dimensional Zeeman Effect in the Magneto-optical Absorption Spectrum for Quantum Dot - Impurity Center Systems

Magneto-optical properties of the quantum dot - impurity center (QD-IC) systems synthesized in a transparent dielectric matrix are considered. For the QD one-electron state description the parabolic model of the confinement potential is used. Within the framework of zero-range potential model and the effective mass approach, the light impurity absorption coefficient for the case of transversal polarization with respect to the applied magnetic field direction, with consideration of the QD size dispersion, has been analytically calculated. It is shown that for the case of transversal polarization the light impurity absorption spectrum is characterized by the quantum dimensional Zeeman effect.

cond-mat.str-el↗

arXiv2002

Magnetic Freezing Effect for the Ground State of Quantum Dot

Within the framework of zero-range potential model in the ap-proach of effective mass, the impurity absorption by the complex Quantum Dot-Impurity Center in an external constant uniform magnetic field is considered. Under condition that the influence of a magnetic field on the ground state of quantum dot is negligible, we have derived the light absorption coefficient of impurity for the case of longitudinal polarization. It is shown that with an increase of the intensity of magnetic field the threshold of an impurity absorption band is shifted to the short-wave spectrum region. Also, the absorption coefficient increases by several times that can be explained as a result of the "magnetic freezing" effect for the ground state of quantum dot.

cond-mat.mes-hall↗