Properties of MnSb/GaAs heterostructures

MnSb layers are deposited on GaAs(100) via the laser ablation of Mn and Sb targets. The magnetic field dependences of the transverse Kerr effect display magnetic anisotropy and magnetization jumps. Measurements of the Hall effect reveal a hysteresis loop at temperatures of up to 300 K.     

Properties of CoPt ferromagnetic layers for application in spin light-emitting diodes

The magnetic properties of Co₄₅Pt₅₅ films deposited by electron-beam evaporation in vacuum have been studied. The measurements of the Faraday and Kerr magnetooptical effects confirm the presence of the easy-magnetization axis perpendicular to the Co₄₅Pt₅₅ surface. It is shown that the perpendicular magnetic anisotropy and the residual magnetization are retained at 300 K for a long time. The magnetic characteristics of the Co₄₅Pt₅₅ layer surface have been studied by magnetic force microscopy, and “circular” mobile magnetic structures have been detected. The spin light-emitting diodes based on In(Ga)As/GaAs heteronanostructures with Co₄₅Pt₅₅ contact layers were fabricated. These diodes emit circularly-polarized light in the absence of an external magnetic field.     

Formation of the single-phase ferromagnetic semiconductor (Ga,Mn)As by pulsed laser annealing

It is shown that (Ga,Mn)As layers formed by Mn⁺ ion implantation into GaAs and subsequent annealing by an excimer laser pulse with an energy density to 200–300 mJ/cm² feature the properties of the p-type semiconductor and ferromagnetic properties. The threshold dose of implanted ions (~10¹⁵ cm^–2) for activating Mn acceptors is determined. The sheet hole concentration and the Curie temperature increase with further increasing Mn⁺ ion dose. Hysteresis loops in the magnetic field dependences of the Hall effect, the negative magnetoresistance, and magnetic and structural studies suggest that the layers are analogues of single-phase ferromagnetic compounds (Ga,Mn)As formed by low-temperature molecular beam epitaxy.     

Photoconductive detector of circularly polarized radiation based on a MIS structure with a CoPt layer

Physics of the Solid State - A photoconductive detector of circularly polarized radiation based on the metal–insulator–semiconductor structure of CoPt/(Al2O3/SiO2/Al2O3)/InGaAs/GaAs is...     

Investigation of heat transfer from a lead heat carrier to a tube streamlined longitudinally

Results of experimental studies on the local characteristics of heat transfer from a lead heat carrier to the surface of a cooled tube in an annular gap are shown at control and alteration of oxygen admixture content under the conditions of power circuits with heavy liquid-metal heat-transfer agent. This work is aimed at obtaining the grounded formulas for engineering calculations of heat transfer surfaces. Investigations were carried out at the lead temperature of 400–500 °C, the average velocity of heat-transfer agent of 0.1–1.5 m/s, the range of Prandtl number of 0.0123–0.0211 and Peclet numbers of 500–7000. The heat flux changed within 50–160 kW/m². Controllable changing content of oxygen admixture changed from the value of thermodynamic activity of oxygen from 10⁻⁵-10⁰ to saturation and higher with deposition of lead oxides near the heat-transferring surface.     

Ferromagnetism in InMnAs layers at room temperature

The InMnAs layers with ferromagnetic properties at room temperature are prepared by laser ablation. This is confirmed by the results of investigating the anomalous Hall and magneto-optical Kerr effects and by magnetic-force microscopy. According to x-ray diffraction data, the InMnAs layers have a fairly high crystal quality but contain inclusions of the MnAs hexagonal phase. An analysis of the electrical properties of the InMnAs layers suggests that the ferromagnetism revealed at room temperature cannot be accounted for by the presence of the MnAs phase but is associated with the charge carrier transfer in the InMnAs matrix.     

VHF current distribution on a cylindrical VLF antenna in a magnetoplasma

We obtain, solution for the current distribution on a linear antenna excited by a given e.m.f. The antenna is an infinitely, long, perfectly conducting cylinder immersed in a plasma and aligned with an external magnetic field. The obtained current distribution in the VLF band is contributed by the eigenmode guided by the cylinder and waves of the continuous spatial spectrum. We show that the current distribution of a sufficiently thin antenna is determined mainly by the eigenmode. The antenna current is calculated both analytically and numerically under ionospheric conditions. The validity criteria for using the transmission-line theory to obtain the current distribution on a linear antenna in a magnetoplasma are discussed. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 8, pp. 750–764, August 1999.     

Formation of half-metallic MnAs and MnP layers

Half-metallic MnAs and MnP layers were grown on GaAs substrates by the laser sputtering of a metal Mn target in a hydrogen and arsine (phosphine) flow. The effect of the arsine concentration in the gascarrier and the substrate temperature (T _g = 300—450°C) on the crystal structure and electrical and magnetic properties were determined. It was shown that MnP samples grown at T _g ≥ 400°C exhibit ferromagnetic properties up to 300 K, according to Hall effect measurements.     

Electronic Transition Dipole Moments in Relativistic Coupled-Cluster Theory: the Finite-Field Method

The determination of the matrix elements of single-electron operators for the transitions between electronic states (primarily, the dipole moments of electron transitions) is one of the critical problems in simulating the atomic and molecular spectra. In this study, the efficiency of a simple version of the finite-field method for calculating these values within the Fock-space coupled-cluster theory has been investigated.