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We report the experimental demonstration of a magnetologic gate built on graphene at room temperature. This magnetologic gate consists of three ferromagnetic electrodes contacting a single-layer graphene spin channel and relies on spin injection and spin transport in the graphene. We utilize electrical bias tuning of spin injection to balance the inputs and achieve "exclusive or" (xor) logic operation. Furthermore, a simulation of the device performance shows that substantial improvement towards spintronic applications can be achieved by optimizing the device parameters such as the device dimensions. This advance holds promise as a basic building block for spin-based information processing.

Extraction of electrons from a semiconductor to a ferromagnet as well as the case of injection in the reverse direction may be formulated as a scattering theory. However, the presence of bound states at the interface arising out of doping on the semiconductor side must be taken into account in the scattering theory. Inclusion of the interface states yields an explanation of a recent result of spin-imaging measurement which contradicts the current understanding of spin extraction. The importance of an extraction theory to spintronics is illustrated by an application to a spin switch.

The helicity of a circularly polarized light beam may be determined by the spin direction of photoexcited electrons in a III-V semiconductor. We present a theoretical demonstration on how the direction of the ensuing electron spin polarization may be determined by electrical means of two ferromagnet/semiconductor Schottky barriers. The proposed scheme allows for the time-resolved detection of spin accumulation in small structures and may have a device application. (c) 2006 American Institute of Physics.

We apply an analysis of time-dependent spin-polarized current in a semiconductor channel at room temperature to establish how the magnetization configuration and dynamics of three ferromagnetic terminals, two of them biased and third connected to a capacitor, affect the currents and voltages. In a steady state, the voltage on the capacitor is related to spin accumulation in the channel. When the magnetization of one of the terminals is rotated, a transient current is triggered. This effect can be used for electrical detection of magnetization reversal dynamics of an electrode or for dynamical readout of the alignment of two magnetic contacts.

A current problem in semiconductor spin-based electronics is the difficulty of experimentally expressing the effect of spin-polarized current in electrical circuit measurements. We present a theoretical solution with the principle of transference of the spin-diffusion effects in the semiconductor channel of a system with three magnetic terminals. A notable result of technological consequences is the room-temperature amplification of the magnetoresistive effect, integrable with electronics circuits, demonstrated by computation of current dependence on magnetization configuration in such a system with currently achievable parameters.

A one-dimensional (1D) theory of lateral spin-polarized transport is derived from the two-dimensional flow in the vertical cross section of a stack of ferromagnetic and paramagnetic layers. This takes into account the influence of the lead on the lateral current underneath, in contrast to the conventional 1D modeling by the collinear configuration of lead/channel/lead. Our theory is convenient and appropriate for the current in-plane configuration of an all-metallic spintronics structure as well as for the planar structure of a semiconductor with ferromagnetic contacts. For both systems we predict the optimal contact width for maximal magnetoresistance and propose an electrical measurement of the spin-diffusion length for a wide range of materials.