Guided by the internal-reference rule and the known band o sets in - and - diluted magnetic semiconductors, we discuss the feasibility of obtaining p-type conductivity, required for the carrier-induced ferromagnetism, as well as the cases for which the doping by shallow impurities may lead to the ferromagnetism driven by the double exchange. e consider the dependence of kinetic exchange on the p-d hybridization, on the electronic con gurations of the magnetic ions, and on the energies of the charge transfer betw een the valence band of host materials and the magnetic ions. n the case of n-based - compounds, the doping by acceptors is necessary for the hole-induced ferromagnetism. he latter is, how ever, possible without any doping for some of Mn-, Fe- or Co-based - magnetic semiconductors. n nitrides with Fe or Co carrier-induced ferromagnetism with TC > 300 is expected in the presence of acceptor doping.

Ti1-xCoxO2 material has reported to show ferromagnetosmat room temperature. Thus, there is research interest in synthesis and structural properties of thismaterial system. The material is synthesized using a soulution chemistry route. X-ray diffraction and Raman spectroscopy is used for the structural characterization.

We propose a new electronic device utilizing resonant tunneling between two magnetic materials. The device is comprised of a semiconductor quantum well sandwiched between two insulating barriers and two ferromagnetic electrodes. The situation in which a resonant level fits in the energy interval where the minority density of states of a ferromagnetic emitter is zero can be considered as an almost ideal spin valve and leads to a great enhancement of magnetoresistance. This situation can be achieved by tuning the width of the quantum well. As an example we will consider GaMnAs/AlAs/GaAs/AlAs/GaMnAs double-barrier heterostructure. We can demonstrate that at a certain thickness of the quantum well and the barriers this system can significantly outperform conventional tunneling junctions comprised of one insulating barrier sandwiched between two ferromagnetic electrodes.

When a spin-polarized current is injected into a non-magnetic semiconductor, a transverse electric field known as Hall voltage is generated. By using a macroscopic diffusion equation, we derive the Hall voltage in the presence of both spin current and magnetic field. Novel features such as oscillating Hall signals as a function of the magnetic field and geometrical dependence of Hall signals are predicted.

We review the results of measurements of spin-memory loss (spin-flipping) at cryogenic temperatures in sputtered or electrodeposited ferromagnetic and non-magnetic metals and alloys, and at metallic interfaces, using the current perpendicular to plane (CPP) geometry.

In this paper, the structural, magnetic and electronic properties of single-crystalline NiMnSb thin films grown by molecular beam epitaxy are presented. The growth process and surface morphology were studied by RHEED and STM. The structural quality of the films was investigated by EXAFS and HRTEM. For the optimized growth conditions, the expected NiMnSb C1b structure was obtained. Moreover, the most stable surface was found to be 4x1 reconstructed. The magnetic and electronic properties were studied by X-ray magnetic circular dichroïsm and spin-resolved x-ray photoemission spectroscopy experiments. The magnetization was observed to be essentially due to Mn, in agreement with theory. The surface was not found to be fully polarized but a polarization near 50% at room temperature was observed. Finally, the preparation of fully epitaxial NiMnSb/MgO/NiMnSb(001) trilayers is presented.

The photogalvanic effects, which require a system lacking inversion symmetry, become possible in SiGe based quantum well (QW) structures due to their built-in asymmetry. We report on observations of the circular and linear photogalvanic effects induced by infrared radiation in (001)-and (113)-orientedp–Si/Si1–xGex QW structures and analyse these observations in view of the possible symmetry of these structures. The circular photogalvanic effect arises due to optical spin orientation of free carriers in QWs with band splitting in k-space which results in a directed motion of free carriers in the plane of the QW. We discuss possible mechanisms that give rise to spin-splitting of the electronic subband states for different symmetries.