706 research outputs found
Renormalization of hole-hole interaction at decreasing Drude conductivity
The diffusion contribution of the hole-hole interaction to the conductivity
is analyzed in gated GaAs/InGaAs/GaAs heterostructures. We show
that the change of the interaction correction to the conductivity with the
decreasing Drude conductivity results both from the compensation of the singlet
and triplet channels and from the arising prefactor in the
conventional expression for the interaction correction.Comment: 6 pages, 5 figure
Electric fields in plasmas under pulsed currents
Electric fields in a plasma that conducts a high-current pulse are measured
as a function of time and space. The experiment is performed using a coaxial
configuration, in which a current rising to 160 kA in 100 ns is conducted
through a plasma that prefills the region between two coaxial electrodes. The
electric field is determined using laser spectroscopy and line-shape analysis.
Plasma doping allows for 3D spatially resolved measurements. The measured peak
magnitude and propagation velocity of the electric field is found to match
those of the Hall electric field, inferred from the magnetic-field front
propagation measured previously.Comment: 13 pages, 13 figures, submitted to PR
Methodology for building the optimal test bench of software and hardware complexes of control systems
The paper considers the issue of creating unified approaches to building test stands for software and hardware control systems. A universal architecture of the test bench is proposed and the author's method of constructing optimal test stands, obtained as a result of research in the field of complex automation of the test process, is described. The algorithm of directed search for the best test stand configuration is considered by example and the results of the implementation of the proposed method are demonstrated. © Published under licence by IOP Publishing Ltd
Experimental and theoretical investigations on magnetic and related properties of ErRuSi
We report experimental and theoretical studies of magnetic and related
properties of ErRuSi compound. Various experimental techniques such as neutron
diffraction, magnetization, magneto-thermal, magneto-transport, optical have
been used to study the compound. Neutron diffraction shows ferromagnetic
ordering at low temperatures with moments aligned in ab plane. Neutron
diffraction and magnetization data show reduction in magnetic moment, which may
be due to crystalline electric field effects at low temperatures. The compound
shows good magnetocaloric properties with a low field adiabatic temperature
change of 4.7 K, which is larger than that of many proposed materials for
magnetic refrigeration at low temperatures. Magnetoresistance shows large
negative value at 8 K, which changes its sign and increases in magnitude, with
decrease in temperature and/or increase in field. The positive MR at low
temperatures attributed to the Lorentz force effect. The electronic structure
calculations accounting for electronic correlations of the 4f electrons of Er
reproduces the ferromagnetic ordering and effective magnetic moment. Interband
transitions between the Ru and Er d states and Er f states in one spin
projection are found to form the main features of the measured optical
conductivity in this compound.Comment: 14 pages, 10 figure
System analysis and processing of parameters of the test bench
The paper deals with the analysis of complex technical objects - test stands of control systems. A method is proposed for evaluating the effectiveness of the test bench based on the parameters obtained using the "standard"and "automated"test stand model. The objective function for calculating the efficiency of test benches based on their parameters and determining the numerical efficiency coefficient of the testing position relative to the typical one is given. The composition of the software for implementing the proposed method is shown. © Published under licence by IOP Publishing Ltd
Photon echo in the ensemble of semiconductor quantum dots spread on a glass substrate
Simple procedure to prepare samples containing semiconductor quantum dots was developed. Test photon echo measurements in the ensemble of quantum dots spread on a glass substrate were performed to study optical dephasing processes
Effect of electronic correlations on the electronic structure, magnetic and optical properties of the ternary RCuGe compounds with R = Tb, Dy, Ho, Er
In this study, the ab initio and experimental results for RCuGe ternary intermetallics were reported for R = Tb, Dy, Ho, Er. Our theoretical calculations of the electronic structure, employing local spin density approximation accounting for electron-electron correlations in the 4f shell of Tb, Dy, Ho, Er ions were carried in DFT+U method. The optical properties of the RCuGe ternary compounds were studied at a broad range of wavelengths. The spectral and electronic characteristics were obtained. The theoretical electron densities of states were taken to interpret the experimental energy dependencies of the experimental optical conductivity in the interband light-absorption region. From the band calculations, the 4f shell of the rare-earth ions was shown to provide the major contribution to the electronic structure, magnetic and optical properties of the RCuGe intermetallics. The accounting for electron-electron correlations in Tb, Dy, Ho, Er resulted in a good agreement between the calculated and experimental magnetic and optical characteristics. © 2020 by the authors.Russian Science Foundation, RSF: 18-72-10098Ministry of Science and Higher Education of the Russian Federation: AAAA-A18-118020190098-5, DST/INT/RFBR/IDIR/P-01/2016The theoretical studies are supported by the Russian Science Foundation, project grant No. 18-72-10098. The optical studies are supported by Ministry of Science and Higher Education of the Russian Federation (theme "Electron" No. AAAA-A18-118020190098-5). K.G.S. acknowledges financial support through Indo-Russian project: DST/INT/RFBR/IDIR/P-01/2016
Spin-splitting in the quantum Hall effect of disordered GaAs layers with strong overlap of the spin subbands
With minima in the diagonal conductance G_{xx} and in the absolute value of
the derivative |dG_{xy}/dB| at the Hall conductance value G_{xy}=e^{2}/h,
spin-splitting is observed in the quantum Hall effect of heavily Si-doped GaAs
layers with low electron mobility 2000 cm^2/Vs in spite of the fact that the
spin-splitting is much smaller than the level broadening. Experimental results
can be explained in the frame of the scaling theory of the quantum Hall effect,
applied independently to each of the two spin subbands.Comment: 4 pages, 4 figure
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