Detailed measurements of the Hall effect in the paramagnetic phase of Ho
0.8
Lu
0.2
B
12
antiferromagnet at the magnetic field up to 80 kOe in the temperature range of 1.9–300 K have been performed. ...It has been found that the transition to the cage glass phase (
T
<
T
* ~ 60 K) is accompanied by the appearance of a positive Hall resistance component in addition to that corresponding to the negative Hall effect. The amplitude and angular dependence of the former depend on the magnitude and direction of the applied magnetic field with respect to the crystallographic axes. The revealed anisotropy of the Hall effect in Ho
0.8
Lu
0.2
B
12
is attributed to the interaction of charge carriers with dynamic charge stripes.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This article further develops the Coulson-Fischer formalism in conjunction with the optimised effective potential method V.N. Glushkov and S. Wilson, Molec. Phys. 110, 149 (2012) to incorporate both ...exchange and static correlation effects for excited states having the same symmetry as the ground state. By using this formalism, we compute complete potential energy curves for the ground and first excited states of the
molecule and the isoelectronic heteronuclear
ion. Effective potentials are generated in according to a novel density functional theory A.K. Theophilou, J. Chem. Phys. 149, 074104 (2018) in which the Kohn-Sham (KS) like potential has spherical symmetry around each nucleus. In this way, the inconsistencies of standard density functional theory concerning the asymmetry of the KS potential are remedied. In our implementation, an effective potential which satisfies this requirement is expressed as a direct mapping of the external potential. Different approximations for the effective potentials are investigated. It is shown that applications of the proposed formalism support good agreement with the exact Coulson-Fischer theory for both the ground and first excited state potential energy curves and thus a qualitatively correct description of dissociation.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
33.
Surface conductivity in SmB6 Glushkov, V.V.; Zhurkin, V.S.; Bozhko, A.D. ...
Solid state sciences,
August 2023, 2023-08-00, Volume:
142
Journal Article
Peer reviewed
We present a study of low temperature electron transport (resistivity, magnetoresistance and Hall coefficient) in SmB6 single crystals having different polar (100) and nonpolar (110) and (111) ...surfaces after mechanical polishing and chemical etching. The estimation of effective parameters for surface and bulk charge carriers allows us to conclude that surface conductivity is very sensitive to the method of surface treatment. The most pronounced change is observed for the polar (100) surface, for which the related Hall concentration of charge carriers at 2 K decreases more than by 2 orders of magnitude and the Hall mobility increases by a factor of 15 after etching these faces in diluted nitric acid. We suggest that the strong dependence of surface properties on the type of treatment may result from both topological protection, which is influenced by intrinsic defects or surface reconstruction, and band bending effects, which modulate the properties of the surface conduction layer in case of polar faces.
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•Surface conductivity in SmB6 is very sensitive to the method of surface treatment.•Etching of polar (100) surface induces 15-fold rise of Hall mobility in SmB6.•Surface magnetoresistance in SmB6 depends on polarity of crystal planes.
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•A Josephson junction under the influence of a weak periodic driving signal and noise was analyzed.•The double minima versus driving signal frequency of the mean switching time and the standard ...deviation are transformed into a single minimum with decreased driving amplitude.•The resonant nature of escape allows detecting weak signals, such that the total current is smaller than the critical current of a Josephson junction.•The possibility to elaborate a single photon counter for microwave frequency range based on aluminum Josephson junction is discussed.
The Josephson junction as a switching detector of weak signals is investigated in presence of noise in the frame of rotating pendulum model. The parameter range, where the detection can be more efficient, is found. It has been demonstrated, that with decrease of the signal power the double minima of the mean switching time and the standard deviation are transformed into a single minimum, which corresponds to interplay between noise suppression and resonant activation regimes. The resonant nature of escape allows to detect weak signals, whose amplitudes are weaker than the difference between critical current and bias current of a Josephson junction. With decrease of damping an efficient detection becomes possible even at subharmonics of the resonance frequency.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Lateral distribution functions of particles in extensive air showers with the energy
eV recorded by ground-based and underground scintillation detectors with a threshold of
GeV at the Yakutsk array ...during the continuous observations from 1986 to 2016 have been analyzed using events with zenith angles θ ≤ 60°. Experimental functions have been compared to the predictions obtained with the QGSJet-01-d hadron interaction model by applying the CORSIKA code. The entire dataset indicates that cosmic rays consist predominantly of protons.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
—
The excitation and propagation of surface acoustic waves in multilayer waveguides with arbitrary anisotropy of elastic layers is considered. A brief survey of the asymptotic representations ...obtained in the framework of the integral approach developed by V.A. Babeshko is given in comparison with the results of classical modal analysis. Examples of applications to the problems of ultrasonic nondestructive testing and structural health monitoring of composite materials are given.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Global problems of effective coal and oil processing waste recovery can be solved by making use of these wastes as the main fuel components for coal water slurries containing petrochemicals (CWSP). ...Until now, no predictive models have been developed that would simulate the sustainable ignition of CWSPs based on components with highly different properties, such as ash, moisture, and volatile content, heat of combustion, etc. This is exactly the type of model we are presenting in this paper. In order to gain a greater insight in the process under study, the experimental research has been conducted. We have created an experimental database with the main characteristics of CWSP ignition, namely the duration of stages, gas-phase and heterogeneous ignition delay times, maximum combustion temperatures, and minimum sufficient oxidizer temperatures. A mathematical model has been developed predicting the conditions and characteristics of CWSP droplet ignition. The signature feature of the model is that it accounts for all the main heat and mass transfer processes and chemical reactions in the solid fuel – liquid fuel – water system under study. This mathematical model can serve as the basis for estimating and comparing the ignition characteristics of different CWSPs.
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•Patterns of CWSP droplet ignition were identified by high-speed video recording.•Ignition characteristics were established for CWSP with different components.•New experimental database contains the main characteristics of CWSP ignition.•Mathematical model describes the physical and chemical processes during induction period.•Mathematical model predicts the characteristics of the CWSP droplet ignition.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract
Electron spin resonance (ESR) in strongly correlated metals is an exciting phenomenon, as strong spin fluctuations in this class of materials broaden extremely the absorption line below the ...detection limit. In this respect, ESR observation in CeB
6
provides a unique chance to inspect Ce
3+
magnetic state in the antiferroquadrupole (AFQ) phase. We apply the original high frequency (60 GHz) experimental technique to extract the temperature and angular dependences of
g
-factor, line width and oscillating magnetization. Experimental data show unambiguously that the modern ESR theory in the AFQ phase considering the Γ
8
ground state of Ce
3+
ion completely fails to predict both the
g
-factor magnitude and its angular dependence. Alignment of the external magnetic field along 100 axis induces a strong (more than twofold) broadening of ESR line width with respect to the other crystallographic directions and results also in the anomalous temperature dependences of the
g
-factor and oscillating magnetization. In this experimental geometry the latter parameter surprisingly exceeds total static magnetization by 20% at
T
* ~ 2.5 K. We argue that the unusual physical picture of ESR in CeB
6
may be strongly affected by spin fluctuations and dynamic collective effects predominantly pronounced in 100 direction.
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This experimental research studies the ignition of fuel particles (droplets) in a high-temperature air medium. Two groups of fuel compositions are considered: the first one is based on kerosene, the ...second one is based on diesel fuel, with gellant (silicon dioxide) and drag-reducing agent (polyhexene) added to them, respectively. The following compositions were used: K-100 (100% kerosene), K-99 (1 wt% silicon dioxide), K-95 (5 wt% silicon dioxide), K-90 (10 wt% silicon dioxide), K-85 (15 wt% silicon dioxide), D-100 (100% diesel fuel), D-FTA (0.04 wt% ForeFTA drag-reducing agent according to TU 2458-002-10022,712-2015), and D-FTA02 (0.04 wt% ForeFTA-02 drag-reducing agent according to TU 20.59.42-015-10022,712-2018). Fuels K-100, D-100, D-FTA, and D-FTA02 behave like Newtonian fluids with constant viscosity vs. shear rate. Kerosene gels K-99 and K-95 behave like non-Newtonian fluids, exhibiting a shear-thinning property, and decrease in viscosity with an increase in the shear rate. Kerosene gels K-90 and K-85 are incapable of flowing and appear to be “solids”. Single fuel particles (droplets) were ignited in a heated air medium at temperatures 873–1273 K. Using a system of high-speed video recording, we established that at various initial temperatures of the compositions, different in the concentrations and appearance of fuel components, an identical set of physical and chemical processes occurs during the induction period, whose duration corresponds to the ignition delay time. These are roughly the same as the processes, occurring when liquid fuels are ignited in a normal state (without gellants or agents). The lowest temperature of heated air, at which fuel compositions are ignited, is 873 K. This value can be notionally referred to as the auto-ignition temperature of fuel when conducting the experiments under the said conditions. The ignition delay times for K-100 and K-99 droplets are identical, whereas for K-95, K-90, and K-85, they are 10–30% longer than the induction period for liquid fuel droplets in a normal state. Compositions based on diesel fuel with 0.04% of drag-reducing agent feature puffing of droplets, when heated, though this process does not affect ignition delay times as the main process characteristic.
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•Two groups of fuel compositions, based on kerosene with gellant and on diesel with drag-reducing agent, were produced.•Ignition mechanisms of fuel compositions in each group are identical.•Kerosene-based compositions have 10–30% longer ignition delay times with an increase in gellant concentration.•Compositions based on diesel and drag-reducing agent are characterized by droplet dispersion, when ignited.
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The article considers the thermal shock of large elastic elements of a spacecraft leaving the Earth's shadow. The stress–strain state of the element is analyzed to estimate additional ...microaccelerations from a thermal shock. Beside the most dangerous cases, the possible initial deflection of the elastic element at the time of the thermal shock is also considered. This deflection can be related to the natural vibrations of elastic elements. The obtained results demonstrate a significant decrease in additional microaccelerations from a thermal shock at certain values of the initial deflection. It was also found that an elastic element can lose stability when bending stresses are added to thermal stresses. The results of the investigation can be used in the design and usage of small technological spacecraft.
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