Emitting heterostructures with a bilayer InGaAs/GaAsSb/GaAs quantum well and a GaMnAs ferromagnetic layer

The radiative and magnetic properties of novel heterostructures with a bilayer InGaAs/GaAsSb/GaAs quantum well and a GaMnAs ferromagnetic layer are studied. The circular polarization of electroluminescent radiation is observed at temperatures from 10 to 160 K. The magnetic field dependences of the degree of circular polarization are nonlinear with a hysteresis loop at temperatures from 10 to 50 K, and they become linear at higher temperatures. The magnitude of polarization at the saturation magnetization of GaMnAs in the 2000 Oe field remains at the level of ~0.2%.     

Ionization formation of plasma inhomogeneity by the near-zone field of a magnetic-type source in a magnetized plasma

An investigations is made of the steady-state structure of a plasma inhomogeneity arising as a result of high-frequency heating and additional ionization of a background magnetized plasma by the near-zone field of a magnetic-type source (ring electric current). It is assumed that the source axis is parallel to an external magnetic field; the source frequency belongs in the low hybrid band. The main attention is focused on the particular case (important for possible applications) when the characteristic longitudinal and transverse scales of density distribution considerably exceed the corresponding scales of distribution of the electron temperature and of the source field. Simplified equations for the near-zone field of the source, the electron temperature, and the plasma density are written for this particular case. Based on the numerical solution of these equations, steady-state distributions of plasma parameters in the formed plasma inhomogeneity are found. It is demonstrated that a plasma inhomogeneity proves to be markedly extended along the external magnetic field. It is found that, for the values of the source current that are attainable under the conditions of active ionospheric and model laboratory experiments, the maximum plasma density in a nonuniform plasma may appreciably exceed the background value.     

Internal Friction in Glass Fiber- and Carbon Fiber-Reinforced Composites with a T-107 Matrix

Technical Physics - The temperature and amplitude dependences of internal friction in hybrid composites consisting of unidirectional carbon fibers and glass tissues in a T-107 molten epoxy matrix...     

Early Diagnosis of Skin Melanoma Using Several Imaging Systems

Optics and Spectroscopy - A complex approach was proposed for early diagnosis of skin melanoma. The approach includes sequential examinations of skin lesions using several imaging systems. A focus...     

Methods for Switching Radiation Polarization in GaAs Laser Diodes

Technical Physics - Operation modes of laser structures with controlled polarization of light have been studied and the results of measuring polarization characteristics are presented. The...     

Magnetoresistance of structures with MnAs layers and <Emphasis Type="Italic">A</Emphasis><Superscript>3</Superscript><Emphasis Type="Italic">B</Emphasis><Superscript>5</Superscript> semiconductors heavily doped with manganese

The magnetotransport properties of epitaxial ferromagnet/semiconductor heterostructures based on MnAs and GaMnAs ferromagnetic layers, separated by a nonmagnetic semiconductor layer (InAs or GaAs), have been investigated. Structures were obtained by combination of laser deposition and metal-organic chemical vapor deposition. A spin-valve effect was observed in magnetoresistance measurements. This fact suggests spin-polarized transport of carriers between ferromagnetic layers.     

Epitaxial growth of MnGa/GaAs layers for diodes with spin injection

The possibility of the epitaxial growth of ferromagnetic manganese gallide (Mn₃Ga₅) layers on a the GaAs(100) surface was demonstrated. The ferromagnetic properties of epitaxial Mn₃Ga₅ at room temperature were evaluated from measurements of the anomalous Hall effect. A diode structure based on the Mn₃Ga₅/GaAs contact was formed, and the low-temperature electroluminescence of this diode was measured. The possibility of electroluminescence and the high crystal quality of the structures under study showed promises of their application in light-emitting diodes with spin injection.     

Dispersion and matching properties of inhomogeneous plasma waveguides

The dispersion characteristics and the field structure of axisymmetric modes channeled by a high-density plasma inhomogeneity stretching along the external magnetic field are determined in the whistler range. The feasibility of matching a small antenna to the background plasma by means of plasma inhomogeneity is demonstrated theoretically and experimentally.Nizhni Novgorod State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 2, pp. 163–172, February, 1991.     

Toward the theory of a loop antenna in an anisotropic plasma

We consider the problem of determining the current distribution along a loop antenna consisting of an infinitely thin perfectly conducting strip coiled into a ring. The antenna is immersed in an anisotropic plasma medium perpendicular to the external magnetic field and is excited by a given EMF. Primary attention is focused on the frequency band in which the excitation of electrostatic waves is possible. The problem is reduced to solving a system of integral equations with logarithmic and singular kernels. Using the solution of these equations, we found expressions for the antenna current distribution and input impedance. The analysis of these expressions is presented. Radiophysical Research Institute, Lobachevsky State University, Nizhny Novgorod, Russia. Translated from izvestiya Vysshikh Uchbnykh Zavedenii, Radiofizika, Vol. 41, No. 3, pp. 358–373, March, 1998.     

Modification of Magnetic Properties of a CoPt Alloy by Ion Irradiation

Physics of the Solid State - The effect of ion irradiation on magnetic properties of films of the ferromagnetic CoPt alloy fabricated by electron-beam evaporation has been studied. It is found that...