Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 30: Focus Session "Spin Currents in Magnetic Nanostructures", Organization: Mathias Kläui (Univ. Mainz)

MA 30.6: Talk

Wednesday, March 28, 2012, 17:30–17:45, EB 301

All-electrical spin injection and detection in lateral Co₂FeSi/GaAs devices — •Pawel Bruski, Rouin Farshchi, Oliver Brandt, Jens Herfort, Abbes Tahraoui, and Manfred Ramsteiner — Paul-Drude-Institut Berlin, Hausvogteiplatz 5-7, 10117 Berlin, Germany

The ferromagnetic Heusler alloy Co₂FeSi is closely lattice matched to GaAs and is predicted to be half-metallic, meaning that electrons at the Fermi level are 100% spin-polarized. We demonstrate the successful all-electrical injection and detection of spins in the Co₂FeSi/GaAs hybrid system using a lateral device structure.

The electrical spin detection is achieved through a nonlocal spin-sensitive measurement, which separates the charge and current paths to exclude parasitic effects such as local Hall effects. Evidence for electrical spin injection and detection has been obtained by spinvalve and Hanle measurements, where the latter presents the most robust proof for all-electrical spin injection and detection by revealing the spin precession in an external magnetic field.

A fit based on a one-dimensional spin drift-diffusion model, which takes into account spin relaxation and precession, is in excellent agreement with our experimental Hanle data. A spin lifetime in GaAs of several ns and a spin injection efficiency of 16% are obtained from the fit, with the latter value being close to results acquired from optoelectronic devices consisting of the Co₂FeSi/(Al,Ga)As hybrid system.