We study the in-plane transport of spin-polarized electrons in III-V semiconductor quantum wells. The spin dynamics is controlled by the spin-orbit interaction, which arises via the Dresselhaus (bulk asymmetry) and Rashba (well asymmetry) mechanisms. This interaction, owing to its momentum dependence, causes rotation of the spin polarization vector, and also produces effective spin dephasing. The density matrix approach is used to describe the evolution of the electron spin polarization, while the spatial motion of the electrons is treated semiclassically. Monte Carlo simulations have been carried out for temperatures in the range 77-300 K.
We develop a Monte Carlo model to study injection of spin-polarized electrons through a Schottky barrier from a ferromagnetic metal contact into a non-magnetic low-dimensional semiconductor structure. Both mechanisms of thermionic emission and tunneling injection are included in the model. Due to the barrier shape, the injected electrons are non-thermalized. Spin dynamics in the semiconductor heterostructure is controlled by the Rashba and Dresselhaus spinorbit interactions and described by a single electron spin density matrix formalism. In addition to the linear term, the third order term in momentum for the Dresselhaus interaction is included.Effect of the Schottky potential on the spin dynamics in a 2 dimensional semiconductor device channel is studied. It is found that the injected current can maintain substantial spin polarization to a length scale in the order of 1 micrometer at room temperature without external magnetic fields. 72.25Dc, 72.25.Hg, 72.25Rb, 2
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We demonstrate theoretically that spin dynamics of electrons injected into a GaAs semiconductor structure through a Schottky barrier possesses strong non-equilibrium features. Electrons injected are redistributed quickly among several valleys. Spin relaxation driven by the spin-orbital coupling in the semiconductor is very rapid. At T = 4.2 K, injected spin polarization decays on a distance of the order of 50 -100 nm from the interface. This spin penetration depth reduces approximately by half at room temperature. The spin scattering length is different for different valleys.
Introduction.Electrical spin injection into a non-magnetic semiconductor structure is one of the most complicated issues in design of semiconductor spintronic devices [1][2][3]. High efficiency of spin injection in magnetic/nonmagnetic semiconductor structures has been demonstrated in the diffusive transport regime [4]. Also, in the ballistic transport regime, spin filtering with a magnetic semiconductor can lead to nearly 100% spin injection [5]. However, at the present stage spin-dependent properties of most of magnetic semiconductors are limited by the low temperature regime only, that strongly restricts their device application. Ferromagnetic metal contacts possess much higher Curie temperature and are more attractive for the application in room temperature spintronic devices. But, in conventional ohmic metal/semiconductor contacts large conductance mismatch [6] prevents efficient injection of spin polarized carriers. One of the solutions
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