Institute of Engineering Physics

The temperature dependence of magnetization is studied to obtain information about the nature of structural and magnetic transformations in amorphous alloys. Low-temperature magnetization provides information on spin waves, i.e., the law of ‘three second’ T3/2 is fulfilled. The spin-wave rigidity constant D, a characteristic property of an amorphous ferromagnetic, is determined from these dependencies.

In this work, the results of the magnetization of the amorphous alloy
FeCrB and the temperature dependence of the Hall coefficient are presented. Based on the experimental results obtained, the relationship between the anomalous Hall coefficient and the specific electrical resistance r and magnetization was studied and showed that the Kondorsky-Vedyaev theory for ferromagnetic crystal samples could also be applied to the amorphous state.

Измерена температурная зависимость магнитной восприимчивости сплавов системы Ni-Mn-Fe-Ga методом Фарадея в интервале температур (20-1000 оС). Установлено, что зависимость χ-1(T) подчиняются закону Кюри-Вейсса. Для исследованных образцов найдены парамагнитная температура Кюри, постоянная Кюри и рассчитаны магнитные моменты, соответствующие химической формуле сплавов.
Ключевые слова: парамагнитная температура Кюри, постоянная Кюри, магнитная восприимчивость, магнитный момент.

В настоящей работе изучены структурные особенности ряда сплавов на основе металлов группы железа в аморфном состоянии с целью установления отличий в их структурах при изменении температуры и состава сплавов. Изучены также такие физические свойства, как температурные зависимости удельного электросопротивления , коэффициента термо-ЭДС S, аномального коэффициента Холла RS, намагниченности насыщения IS и кривой дифференциального термического анализа (ДТА) сплавов 𝐹𝑒40𝑁𝑖38𝑀𝑜4𝐵18 и Fe44,2Ni44,2Mo7.65B3,95 Для объяснения характера изменения физических свойств дополнительно изучались структурные превращения, протекающие в сплаве при его нагреве с постоянной скоростью и при изотермическом отжиге.

In this work the changes in the electrophysical, galvanomagnetic and magnetic properties of Fe70Cr15B15; Fe73Cr12B15; Fe75Cr10B15; Fe77Cr8B15 amorphous alloys under the influence of temperature, changes in these properties in the phase transition region, and the relationship between their electrophysical, galvanomagnetic and magnetic properties were studied. In the temperature range from room temperature to 800 K, the specific electrical resistance ρ in the amorphous state is greater than in their crystalline state, and the resistance temperature coefficient (RTС) in the amorphous state is smaller than in the crystalline state

It have been experimentally studied the temperature dependences of the effective Hall coefficient of amorphous alloys Fe73Cr12B15 and Fe75Cr10B15 based on 3d elements, obtained from the liquid state by ultra-fast cooling, using the Van der Pauw method in the temperature range of 300-773K are experimentally studied. The temperature dependence of the electrical resistivity of the samples was studied using the four-probe method in the temperature range 300-773K. The temperature dependence of the specific magnetization of the samples has been studied experimentally using a vibration magnetometer at temperatures of 300-1100K at sample heating rates of 10, 20 and 40 K/min. It is found that the ferromagnetism-paramagnetism phase transition temperatures of the samples have a complete correlation with the results of the Hall coefficient, resistivity and specific magnetization, and the amorphous-crystalline phase transition temperatures vary depending on the heating rate. The results of the mutual and temperature dependence of the electrical, magnetic and galvanomagnetic properties of the samples are analyzed.

A study is performed of the temperature dependences of the Hall coefficient, specific electrical resistance, and saturation magnetization for Fe60Co20Si8B12 and Fe58Co20Si12B10 alloys in amorphous and crystalline states. The relationship between these parameters is established and explained from the viewpoint of the theory of the anomalous Hall effect. Coefficients of the parameter of spin–orbital interaction are estimated on the basis of experimental data.

Differential scanning calorimetry (DSC) is used to study the phase transformations of four amorphous metal alloys based on transition metals Fe and Ni with additives of Si and C. The temperature dependences of the heat flux upon phase transformations are measured along with changes in the mass and specific heat capacity of amorphous alloys. Two phase transformations associated with the temperature of glass transition and complete crystallization are identified. The relative volume of the crystalline fraction of alloys heated to 1000°C is calculated. It is concluded there are nanocrystalline phases between the first and second phase transitions at heating rates of 0.1°C/s.

Coronal Mass Ejections (CMEs) contributes to the perturbation of solar wind in the heliosphere. Thus, depending on the different phases of the solar cycle and the rate of CME occurrence, contribution of CMEs to solar wind parameters near the Earth changes. In the present study, we examine the long term occurrence rate of CMEs, their speeds, angular widths and masses. We attempt to find correlation between near sun parameters, determined using white light images from coronagraphs, with solar wind measurements near the Earth from in-situ instruments. Importantly, we attempt to find what fraction of the averaged solar wind mass near the Earth is provided by the CMEs during different phases of the solar cycles.

We have studied the consequences of interacting coronal mass ejections (CMEs) of June 13-14, 2012 which were directed towards Earth and caused a moderate geomagnetic storm with Dst index ~ −86 nT. We analysed the in-situ observations of the solar wind plasma and magnetic field parameters obtained from the OMNI database for these CMEs. The in-situ observations show that the interacting CMEs arrive at Earth with the strongest (~ 150 nT) Sudden Storm Commencement (SSC) of the solar cycle 24. We compared these interacting CMEs to a similar interaction event which occurred during November 9-10, 2012. This occurred in the same phase of the solar cycle 24 but resulted in an intense geomagnetic storm (Dst ~ −108 nT), as reported by Mishra et al. (2015). Our analysis shows that in the June event, the interaction led to a merged structure at 1 AU while in the case of November 2012 event, the interacted CMEs arrived as two distinct structures at 1 AU. The geomagnetic signatures of the two case...

Similar to the Sun, other stars shed mass and magnetic flux via ubiquitous quasi-steady wind and episodic stellar coronal mass ejections (CMEs). We investigate the mass loss rate via solar wind and CMEs as a function of solar magnetic variability represented in terms of sunspot number and solar X-ray background luminosity. We estimate the contribution of CMEs to the total solar wind mass flux in the ecliptic and beyond, and its variation over different phases of the solar activity cycles. The study exploits the number of sunspots observed, coronagraphic observations of CMEs near the Sun by SOHO/LASCO, in situ observations of the solar wind at 1 AU by WIND, and GOES X-ray flux during solar cycles 23 and 24. We note that the X-ray background luminosity, occurrence rate of CMEs and ICMEs, solar wind mass flux, and associated mass loss rates from the Sun do not decrease as strongly as the sunspot number from the maximum of solar cycle 23 to the next maximum. Our study confirms a true ph...

Interacting coronal mass ejections (CMEs) have been commonly reported during the STEREO era. With the interaction of CMEs in the heliosphere, it is expected that the participating CMEs will either merge to form a single interplanetary CME (ICME) or will arrive as distinct entities or ICMEs at 1 AU. Previous studies have focused on in situ observations of solar wind, i.e., plasma and magnetic field properties to understand the nature of the CME–CME interaction and its impact. In this study, we examine the observations of composition parameters of those ICMEs that resulted due to the interaction of two CMEs during their propagation between the Sun and the Earth. We report two events of the CME–CME interaction observed in 2012, of which one led to a merged structure after the interaction, as observed at 1 AU. The second interaction event was reported to arrive at L1 as two distinct structures. Our analysis reveals distinct composition signatures in the form of ion charge state enhancements. The results improve our understanding of the signatures of ICMEs and different complex structures formed after the interaction. The study reveals that compression can occur due to the passage of the shock associated with the following CME through the preceding CME and not due to the CME–CME interaction. The results also highlight the importance of the comparison of solar wind proton velocity data with the expected temperature data, in particular, to understand the ICME–ICME interaction processes.

Interacting coronal mass ejections (CMEs) have been commonly reported during the STEREO era. With the interaction of CMEs in the heliosphere, it is expected that the participating CMEs will either merge to form a single interplanetary CME (ICME) or will arrive as distinct entities or ICMEs at 1 AU. Previous studies have focused on in situ observations of solar wind, i.e., plasma and magnetic field properties to understand the nature of the CME–CME interaction and its impact. In this study, we examine the observations of composition parameters of those ICMEs that resulted due to the interaction of two CMEs during their propagation between the Sun and the Earth. We report two events of the CME–CME interaction observed in 2012, of which one led to a merged structure after the interaction, as observed at 1 AU. The second interaction event was reported to arrive at L1 as two distinct structures. Our analysis reveals distinct composition signatures in the form of ion charge state enhancem...

Coronal Mass Ejections (CMEs) contributes to the perturbation of solar wind in the heliosphere. Thus, depending on the different phases of the solar cycle and the rate of CME occurrence, contribution of CMEs to solar wind parameters near the Earth changes. In the present study, we examine the long term occurrence rate of CMEs, their speeds, angular widths and masses. We attempt to find correlation between near sun parameters, determined using white light images from coronagraphs, with solar wind measurements near the Earth from in-situ instruments. Importantly, we attempt to find what fraction of the averaged solar wind mass near the Earth is provided by the CMEs during different phases of the solar cycles.

ABSTRACT The frequency shift Δv of the Mandelstam-Brillouin components in an solution of γ-picoline is studied in relation to the temperature t of the solution (in the range 10–80°C) and the concentration x of γ-picoline (x < 0.1 ppm). The following specific features of the behavior of the quantity Δv are observed: (i) an inversion of the sign of the temperature coefficient of the dependence Δv(t) with a change in the concentration of the solution and (ii) the occurrence of two maxima on the isotherms of the dependence Δv(x), which behave significantly differently with the solution temperature and concentration. These experimental results are discussed from the viewpoint of the manifestation of a phase transition of the structural type in these spectra at small concentrations of γ-picoline in water.

Self-heating in planar double-gate (DG) MOSFETs is numerically studied under static operating conditions. In order to correctly predict the lattice temperature inside the device and, consequently, the drain current, factors such as the reduction in thermal conductivity of thin films (temperature dependent), the influence of the buried oxide layer, the necessity of a hydrodynamic model and quantization are analysed to evidence their impact on a proper simulation of the dc transistor performance. This paper also shows that DG MOSFETs can be thermally optimized using flare extensions in all terminals and mid-gap gate metals with high thermal conductivity. Moreover, the influence of gate length and channel thickness on the peak temperature rise is studied. Other major technological changes, such as eliminating thin oxide films from channel extensions and using AlN instead of SiO 2 , are also discussed.

The influence of two-photon absorption on the stimulated Mandelshtam-Brillouin scattering of light in (beta) -picolin- water solution with a singular point has been studied. Values of two-photon absorption coefficient and the imaginary part of a susceptibility of the solution have been calculated. Temperature dependence of the imaginary part of the susceptibility for analyzed solution has been determined.

ABSTRACT The hypersonic velocity dispersion in aqueous solutions of 4-methylpyridine in the frequency range from 4.7 to 6.1 GHz has been studied by Brillouin scattering spectroscopy. A negative hypersonic velocity dispersion is established for solutions with concentrations of 0.08 and 0.06 molar fractions of 4-methylpyridine.