Electric field control of spin-orbit splittings in GaAs/AlGaAs coupled quantum wells

Electron spin dynamics is investigated in n-i-n GaAs/AlGaAs coupled quantum wells. The electron spin dephasing time is measured as a function of an external electrical bias under resonant excitation of the 1sHH intrawell exciton using a time-resolved Kerr rotation technique. It is found a strong electron spin dephasing time anisotropy caused by an interference of the structure inversion asymmetry and the bulk inversion asymmetry. This anisotropy is shown to be controlled by an electrical bias. A theoretical analysis of electron spin dephasing time anisotropy is developed. The ratio of Rashba and Dresselhaus spin splittings is studied as a function of applied bias.Comment: 4 pages, 3 figure

Improving the methodological tools of market pricing in exhibition marketing

Purpose: The purpose of the study is to determine ways to improve the methodological pricing tools in exhibition marketing from market positions. Design/Methodology/Approach: The leading method of research is a systematic approach, which is used to substantiate the economic and mathematical model of the optimal market price of the exhibition area, which is set depending on the quality of the exhibition. In order to measure differences in the quality of exhibition events, authors proposed to use reference-exhibition benchmarking characterized by the best price / quality ratio. Findings: The results of the study form the methodological basis for improving pricing not only in the exhibition business, but also in other areas of business activity. This is possible if the goods (services) are produced in the conditions of a monopolistic competition, and the quality of an individual product (service) could be quantified in a conventional unit, which should be scientifically substantiated. Practical implications: This study is of practical value for both exhibition organizers and their participants. Using of expo-activities of the developed methodological tools of market pricing allows strengthening their competitive positions and increasing the profitability of exhibitions, if the optimal market price of the exposition calculated by the proposed method compensates the average total costs of the exhibition company. Originality/Value: The article substantiates the original conceptual approach to exhibition pricing, which is based on interaction marketing, benchmarking and extremely high price, which prevents the formation of demand from exhibitors, that is proposed to be called the alternative price. It becomes possible to provide a scientific basis for determining the optimal market price of the exhibition area, that maximizes the profit of the organizing company.peer-reviewe

Suppression of electron relaxation and dephasing rates in quantum dots caused by external magnetic fields

An external magnetic field has been applied in laterally coupled dots (QDs) and we have studied the QD properties related to charge decoherence. The significance of the applied magnetic field to the suppression of electron-phonon relaxation and dephasing rates has been explored. The coupled QDs have been studied by varing the magnetic field and the interdot distance as other system parameters. Our numerical results show that the electron scattering rates are strongly dependent on the applied external magnetic field and the details of the double QD configuration.Comment: 13 pages, 6 figure

Ring-shaped spatial pattern of exciton luminescence formed due to the hot carrier transport in a locally photoexcited electron-hole bilayer

A consistent explanation of the formation of a ring-shaped pattern of exciton luminescence in GaAs/AlGaAs double quantum wells is suggested. The pattern consists of two concentric rings around the laser excitation spot. It is shown that the luminescence rings appear due to the in-layer transport of hot charge carriers at high photoexcitation intensity. Interestingly, one of two causes of this transport might involve self-organized criticality (SOC) that would be the first case of the SOC observation in semiconductor physics. We test this cause in a many-body numerical model by performing extensive molecular dynamics simulations. The results show good agreement with experiments. Moreover, the simulations have enabled us to identify the particular kinetic processes underlying the formation of each of these two luminescence rings.Comment: 14 pages, 16 figures. Final versio

Evidence for T Tauri-like emission in the EXor V1118 Ori from near-IR and X-ray data

We present a near-IR study of the EXor variable V1118 Ori, performed by following a slightly declining phase after a recent outburst. In particular, the near-IR (0.8 - 2.3 micron) spectrum, obtained for the first time, shows a large variety of emission features of the HI and HeI recombination and CO overtone. By comparing the observed spectrum with a wind model, a mass loss rate value is derived along with other parameters whose values are typical of an accreting T Tauri star. In addition, we have used X-ray data from the XMM archive, taken in two different epochs during the declining phase monitored in IR. X-ray emission (in the range 0.5 - 10 keV) permits to derive several parameters which confirm the T Tauri nature of the source. In the near-IR the object maintains a low visual extinction during all the activity phases, confirming that variable extinction does not contribute to brightness variations. The lack of both a significant amount of circumstellar material and any evidence of IR cooling from collimated jet/outflow driven by the source, indicates that, at least this member of the EXor class, is in a late stage of the Pre-Main Sequence evolution. In the X-ray regime, an evident fading is present, detected in the post-outburst phase, that cannot be reconciled with the presence of any absorbing material. This circumstance, combined with the persistence (in the pre- and post-outburst phases) of a temperature component at about 10 MK, suggests that accretion has some influence in regulating the coronal activity

Phase Composition of Mo-Si-V Hypoeutectic Alloys

Thermodynamic modeling (TDM) of phase formation was performed with vanadium doping of the hypoeutectic Mo-Si alloy. It was found that the thermochemical properties of vanadium silicides (presented in the HSC Chemistry 6.12 database), when modeling Mo-Si(14.5-12.2)-V(5.0-20.0) alloys, lead to inadequate results regarding Mo-Si-V diagram state indicators. The simulation results agree satisfactorily with the Mo-Si-V diagram with the following values of ΔH0 298: for V3Si = - 180.4 kJ / mol, for V5Si3 = -433.6 kJ / mol, for VSi2 = -124.5 kJ / mol. According to the results of TDM and X-ray phase analysis (XRD) of the obtained alloys, it was found that vanadium in Mo-Si-V ternary alloys can be found both in the form of silicides, (Mo,V)3Si, and in the composition of the solid solution (Mo,V

Structure and Phase Composition of V-Al-N-C Master Alloy

The article presents the results of studying the phase composition and microstructure of the V-Al-N-C alloy, intended mainly for doping titanium alloys, but also of interest to manufacturers of structural steels. The V-Al-N-C alloy was obtained by the method of out-of-furnace aluminothermic smelting of a mixture containing vanadium pentoxide, aluminum powder, nitrided by the SHS method powdered V-Al-(17-20)N (wt.%) alloy and graphite in copper uncooled molds. The phase composition was determined by X-ray phase analysis (diffractometer - DRON-2.0, radiation - Cu-Kα, monochromator - graphite). The microstructure and composition of the phases were investigated by X-ray microanalysis using a JSM-59000LV scanning electron microscope ( Japan) and an Oxford INCA Energy 200 energy-dispersive X-ray spectrometer (United Kingdom). It is revealed that the matrix of the V-Al-N-C alloy, containing (wt. %): 73.9 V; 23.7 Al, 1.2 N, 0.69 C, and 0.08 O2, are represented by the solid solution of aluminum in vanadium. The main nitrogen-containing phase is aluminum nitride AlN of a cubic structure. The carbide phase can be identified as V2Al0.9C1.1. Nitride and carbide phases are distributed quite uniformly in the alloy matrix. The carbide phase in the structure of the V-Al-N-C alloy is predominantly in the form of threadlike crystals up to 100 μm in length. The nitride phase is represented by small (up to 10 μm) and large (30 ÷ 10

Isovector Collective Response Function of Nuclear Matter at Finite Temperature

We study isovector collective excitations in nuclear matter by employing the linearized Landau-Vlasov equation with and without a non-Markovian binary collision term at finite temperature. We calculate the giant dipole resonance (GDR) strength function for finite nuclei using Steinwedel-Jensen model and also by Thomas-Fermi approximation, and we compare them for 120Sn and 208Pb with experimental results.Comment: 15 pages, 4 figure

Breathing mode in an improved transport approach

The nuclear breathing-mode giant monopole resonance is studied within an improved relativistic Boltzmann-Uehling-Uhlenbeck (BUU) transport approach. As a new feature, the numerical treatment of ground state nuclei and their phase-space evolution is realized with the same semiclassical energy density functional. With this new method a very good stability of ground state nuclei in BUU simulations is achieved. This is important in extracting clear breathing-mode signals for the excitation energy and, in particular, for the lifetime from transport theoretical studies including mean-field and collisional effects.Comment: 33 pages, 11 figures, accepted for publication in Phys. Rev.