Diffusion theory of spin injection through resistive contacts |
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Authors: | EI Rashba |
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Institution: | (1) Department of Physics, The State University of New York at Buffalo, Buffalo, NY 14260, USA, US |
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Abstract: | Insertion of a resistive contact between a ferromagnetic metal and a semiconductor microstructure is of critical importance
for achieving efficient spin injection into a semiconductor. However, the equations of the diffusion theory are rather cumbersome
for the junctions including such contacts. A technique based on deriving a system of self-consistent equations for the coefficients
of spin injection, γ, through different contacts are developed. These equations are concise when written in the proper notations.
Moreover, the resistance of a two-contact junction can be expressed in terms of γ's of both contacts. This equation makes
calculating the spin valve effect straightforward, allows to find an explicit expression for the junction resistance and to
prove that its nonequilibrium part is positive. Relation of these parameters to different phenomena like spin-e.m.f. and the
contact transients is established. Comparative effect of the Coulomb screening on different parameters is clarified. It is
also shown that the spin non-conservation in a contact can have a dramatic effect on the non-equilibrium resistance of the
junction.
Received 2 May 2002 / Received in final form 26 July 2002 Published online 15 October 2002
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ID="a"Also at the Department of Physics, MIT, Cambridge, Massachusetts 02139, USA e-mail: erashba@mailaps.org |
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Keywords: | PACS 72 25 Hg Electrical injection of spin polarized carriers – 72 25 Mk Spin transport through interfaces |
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