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arXiv · 0709.2707

Electrical expression of spin accumulation in ferromagnet/semiconductor structures

L. Cywinski·H. Dery·P. Dalal·L. J. Sham
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Abstract

We treat the spin injection and extraction via a ferromagnetic metal/semiconductor Schottky barrier as a quantum scattering problem. This enables the theory to explain a number of phenomena involving spin-dependent current through the Schottky barrier, especially the counter-intuitive spin polarization direction in the semiconductor due to current extraction seen in recent experiments. A possible explanation of this phenomenon involves taking into account the spin-dependent inelastic scattering via the bound states in the interface region. The quantum-mechanical treatment of spin transport through the interface is coupled with the semiclassical description of transport in the adjoining media, in which we take into account the in-plane spin diffusion along the interface in the planar geometry used in experiments. The theory forms the basis of the calculation of spin-dependent current flow in multi-terminal systems, consisting of a semiconductor channel with many ferromagnetic contacts attached, in which the spin accumulation created by spin injection/extraction can be efficiently sensed by electrical means. A three-terminal system can be used as a magnetic memory cell with the bit of information encoded in the magnetization of one of the contacts. Using five terminals we construct a reprogrammable logic gate, in which the logic inputs and the functionality are encoded in magnetizations of the four terminals, while the current out of the fifth one gives a result of the operation.

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L. Cywinski, H. Dery, P. Dalal, L. J. Sham. 2007-09-17. Electrical expression of spin accumulation in ferromagnet/semiconductor structures. https://doi.org/10.1142/s021798490701395x

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