108 research outputs found
Electroresistive and magnetoresistive properties of Nd0.7Sr0.3MnO3 after quenching under pressure of 9GPa
No full textPolycrystalline Nd0.7Sr0.3MnO3 was quenched from 1300 K to 300 K and 80 K after it had been subjected to a high quasihydrostatic pressure of 9 GPa. Such high pressure and high temperature treatment (HPT) results in significant changes of the crystallochemical parameters-Mn-O lengths and Mn-O-Mn angles within unchanged lattice symmetry of the Pnma-type. A strong increase of the resistivity and a large decrease of the FM-PI transition temperature were detected for the Nd0.7Sr0.3MnO3 HPT treated samples. The intrinsic characteristic T-MI(T-C) (T-MI is the metal-insulator and T-C is the ferromagnetic-paramagnetic transition temperature) correlates with the change of the Mn-O(1)-Mn angle, which is consistent with the double exchange model of the ferromagnetic metallic state in manganites. Remarkable electroresistive (ER) and magnetoresistive (MR) effects appear after HPT treatment, which were not present in the starting Nd0.7Sr0.3MnO3 sample. The structure sensitive properties such as resistivity, MR and ER effects correlate with the change of the nanograin sizes after HPT treatment. Nonlinear current-voltage characteristics showing a hysteresis appear for HPT treated samples at low temperatures. The transport in granular Nd0.7Sr0.3MnO3 samples is likely defined by spin-dependent scattering of charge carriers inside the ferromagnetic metallic grains with embedded small charged isolating islands and by jumping over charged insulating barriers at the intergrain boundaries, which can be strongly affected by the external electric and magnetic fields. (C) 2011 Elsevier B.V. All rights reserved
Magnetic States and Electronic Properties of Manganese-Based Intermetallic Compounds MnYAl and MnZ (Y = V, Cr, Fe, Co, Ni; Z = Al, Ge, Sn, Si, Pt)
No full textWe present a brief review of experimental and theoretical papers on studies
of electron transport and magnetic properties in manganese-based compounds
MnYZ and MnZ (Y = V, Cr, Fe, Co, Ni, etc.; Z = Al, Ge, Sn, Si, Pt,
etc.). It has been shown that in the electronic subsystem of MnYZ
compounds, the states of a half-metallic ferromagnet and a spin gapless
semiconductor can arise with the realization of various magnetic states, such
as a ferromagnet, a compensated ferrimagnet, and a frustrated antiferromagnet.
Binary compounds MnZ have the properties of a half-metallic ferromagnet and
a topological semimetal with a large anomalous Hall effect, spin Hall effect,
spin Nernst effect, and thermal Hall effect. Their magnetic states are also
very diverse: from a ferrimagnet and an antiferromagnet to a compensated
ferrimagnet and a frustrated antiferromagnet, as well as an antiferromagnet
with a kagome-type lattice. It has been demonstrated that the electronic and
magnetic properties of such materials are very sensitive to external influences
(temperature, magnetic field, external pressure), as well as the processing
method (cast, rapidly quenched, nanostructured, etc.). Knowledge of the
regularities in the behavior of the electronic and magnetic characteristics of
MnYAl and MnZ compounds can be used for applications in micro- and
nanoelectronics and spintronics.Comment: Review paper, 27 page
Magnetic States and Electronic Properties of Manganese-Based Intermetallic Compounds Mn2YAl and Mn3Z (Y = V, Cr, Fe, Co, Ni; Z = Al, Ge, Sn, Si, Pt)
No full textWe present a brief review of experimental and theoretical papers on studies of electron transport and magnetic properties in manganese-based compounds Mn2YZ and Mn3Z (Y = V, Cr, Fe, Co, Ni, etc.; Z = Al, Ge, Sn, Si, Pt, etc.). It has been shown that in the electronic subsystem of Mn2YZ compounds, the states of a half-metallic ferromagnet and a spin gapless semiconductor can arise with the realization of various magnetic states, such as a ferromagnet, a compensated ferrimagnet, and a frustrated antiferromagnet. Binary compounds of Mn3Z have the properties of a half-metallic ferromagnet and a topological semimetal with a large anomalous Hall effect, spin Hall effect, spin Nernst effect, and thermal Hall effect. Their magnetic states are also very diverse: from a ferrimagnet and an antiferromagnet to a compensated ferrimagnet and a frustrated antiferromagnet, as well as an antiferromagnet with a kagome-type lattice. It has been demonstrated that the electronic and magnetic properties of such materials are very sensitive to external influences (temperature, magnetic field, external pressure), as well as the processing method (cast, rapidly quenched, nanostructured, etc.). Knowledge of the regularities in the behavior of the electronic and magnetic characteristics of Mn2YAl and Mn3Z compounds can be used for applications in micro- and nanoelectronics and spintronics
The Electronic Structure, Thermoelectric, and Optical Properties of Heusler Alloys Mn2MeAl (Me = Ti, V, Cr)
No full textAbstract: The results of calculations of the electronic structure, thermoelectric characteristics, and experimental study of the thermoelectric, electrical, and optical properties of Mn2MeAl Heusler alloys (Me = Ti, V, Cr) are presented. The agreement between theory and experiment in the sign of the Seebeck coefficient is shown. The obtained pattern of the band spectrum allows us to qualitatively explain the peculiarities of the temperature dependences of the electrical resistance and the permittivity dispersion. © 2023, The Author(s).Ural Branch, Russian Academy of Sciences, UB RAS; Russian Science Foundation, RSF: 22-22-20109This study was supported by a grant from the Russian Science Foundation (project no. 22-22-20109, https://rscf.ru/project/22-22-20109/ , Institute of Metal Physics, Ural Branch, Russian Academy of Sciences)
Unusual Kinetic Properties of Usual Heusler Alloys
No full textThe review considers various groups of Heusler compounds, which can have the properties of a semiconductor, a half-metallic ferromagnet, a spin gapless semiconductor, a topological semimetal, and a non-collinear antiferromagnet. In these Heusler compounds, “conventional” from the point of view of the crystal structure, unusual kinetic and magnetic properties can be observed, which are caused by the features of their electronic structure (e.g., presence of an energy gap for one spin projection) and magnetic state (e.g., strong ferromagnetism, compensated ferrimagnetism). Their magnetic and kinetic characteristics are very sensitive to external influences. Depending on the alloy composition and external parameters, transitions between the considered states can be realized. All this opens up further prospects for controlling the electronic and magnetic characteristics of such compounds and their practical application. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Ministry of Education and Science of the Russian Federation, Minobrnauka: 122021000036–3, 122021000038–7; Russian Science Foundation, RSF: 22–22-00935The research was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (themes “Spin,” No. 122021000036–3 and “Quantum,” No. 122021000038–7). Research funding was provided by the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program). The Sect. was prepared with the financial support of the Russian Science Foundation within the framework of research project No. 22–22-00935
Evolution of the Diagnosis and Treatment of Acute Respiratory Distress Syndrome on the Basis of Up-to-Date Medical Technologies
No full textThe paper generalizes the 15 years’ experience of the V. A. Negovsky Research Institute of General Reanimatology, Russian Academy of Medical Sciences, in conducting fundamental studies of the morphological, functional, and clinical patterns of the development of acute respiratory distress syndrome (ARDS), by using up-to-date medical technologies. The developed and clinically introduced new scientifically grounded methods for the prevention, diagnosis, and combination, differentiated treatment of ARDS could reduce the number of complications, the duration of mechanical ventilation, the length of stay in the intensive care unit, and mortality rates. Key words: acute respiratory distress syndrome, V. A. Negovsky Research Institute of General Reanimatology, Russian Academy of Medical Sciences
Electronic, magnetic and galvanomagnetic properties of Co-based Heusler alloys: Possible states of a half-metallic ferromagnet and spin gapless semiconductor
No full textParameters of the energy gap and, consequently, electronic, magnetic and galvanomagnetic properties in different X2YZ Heusler alloys can vary quite strongly. In particular, half-metallic ferromagnets (HMFs) and spin gapless semiconductors (SGSs) with almost 100% spin polarization of charge carriers are promising materials for spintronics. The changes in the electrical, magnetic and galvanomagnetic properties of the Co2YSi (Y = Ti, V, Cr, Mn, Fe) and Co2MnZ Heusler alloys (Z = Al, Si, Ga, Ge) in possible HMF- and/or SGS-states were followed and their interconnection was established. Significant changes in the values of the magnetization and residual resistivity were found. At the same time, the correlations between the changes in these electronic and magnetic characteristics depending on the number of valence electrons and spin polarization are observed. © 2021 Author(s).The work was performed within the framework of the state assignment of the Ministry of Science and Higher Education of Russia (the themes “Spin,” No. AAAA-A18-118020290104-2-2 and “Quantum” No. AAAA-A18-118020190095-4) with partial support from the RFBR (projects No. 18-02-00739 and 20-32-90065) and the Government of the Russian Federation (Decree No. 211, Contract No. 02.A03.21.0006)
Interrelation between Strains and Parameters of Metal Strengthening upon Tension and Indentation in Plastic Region
No full textRespiratory Therapy for Acute Lung Lesion, by Using Biphasic Positive Pressure Ventilation
No full textObjective. To comparatively study the efficiency of respiratory support in patients with acute lung lesion, by applying BIPAP, SIMV, and aIPPV.Subjects. Twenty-six patients with acute lung lesion whose pattern included acute respiratory distress syndrome (n=16), pneumonia (и=6), and pneumonitis (n=4) were examined. The severity of disease was 18 to 21 APACHE II scale score.Results. The use of BIPAP leads to a better adaptation of a patient to respiratory support, to a reduction in the number of used myorelaxants and sedatives, and to improvement of gas exchange in the lung and diminishes the negative impact of artificial ventilation on hemodynamics. As compared with other types of assisted ventilation, BIPAP accelerates transfer from total respiratory support to spontaneous breathing
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