Spin dynamics in a compound semiconductor spintronic structure with a Schottky barrier

Abstract

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

Noise-induced effects in nonlinear relaxation of condensed matter systems

“…Near the bottom of the L-valleys, located along the [111] direction in the crystallographic axes [121], the precession vector can be written as…”

“…Here, we set β = 23.9 eV ·Å 3 , as in Ref. [120,121] and β L = 0.26 eVÅ · 2/ , as theoretically estimated in Ref. [122].…”

Relaxation of electron spin during high-field transport in GaAs bulk

“…Another way is to use a semiclassical Monte Carlo approach, by taking into account the spin polarization dynamics with the inclusion in the code of the precession mechanism of the spin polarization vector [27,28,29,30,31,32,33,34].…”

Nonlinear Relaxation Phenomena in Metastable Condensed Matter Systems

“…In the equivalent L-valleys located along the [111] crystallographic direction, the precession vector is [149] …”

“…The electron transport dynamics is simulated by a semiclassical Monte Carlo algorithm, which takes into account all the possible scattering events of the hot electrons in the medium [154,155] and includes the precession equation of the spin polarisation vector for each free carrier [149,156,157]. The Monte Carlo algorithm has been implemented by using a Multiparticle Multivalley FORTRAN Code, following the procedure extensively described in [158].…”