Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 18: Poster I : Bio Magn. (1-2); Mag.Imgaging (3-9); Magn. Semiconductors (10-16); Half Metals & Oxides (17-20); Coupl.Phenomena (21-27); Magn. Mat. (28-41); Micro & Nanostr. Magn. Materials (42-61); Micro Magn. (62-64); Surface Magnetism (65-70); Transport Phenomena (71-85)

MA 18.73: Poster

Dienstag, 26. Februar 2008, 15:15–18:30, Poster E

Experiments and theoretical description of spin precession in lateral all-metall spin valves — •Jeannette Wulfhorst, Andreas Vogel, Alexander van Staa, Ulrich Merkt, and Guido Meier — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Jungiusstrasse 11, 20355 Hamburg (Germany)

Via transport measurements at low temperatures and with an external magnetic field we examine spin valves which consist of two ferromagnetic permalloy electrodes and a normal metal strip. Due to the shape anisotropy the electrodes are quasi-single domain and can be oriented parallel or antiparallel to each other. To obtain the coercive fields of the electrodes we have measured the anisotropic magnetoresistance of both. The nonlocal spin-valve effect is determined by using the first electrode to inject a spin-polarized current into the normal metal and to detect it with the aid of the other electrode [1]. With an out-of-plane external magnetic field spin precession, i.e. the Hanle-effect, is observed. The measured data is described by spin-dependent transport including spin diffusion, spin relaxation, spin precession, and tunnel barriers at the interfaces between the electrodes and the normal metal strip [1]. We estimate a spin-diffusion length in aluminum of 1034 nm, and a spin-relaxation time of 111 ps. The aluminum oxide tunnel barrier inbetween those films can enlarge the spin polarization of the injected current [2].

[1] A. van Staa, J. Wulfhorst, U. Merkt and G. Meier, submitted

[2] F.J. Jedema et al., Nature 416, 713 (2002)