Dresden 2006 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)

MA 20.78: Poster

Dienstag, 28. März 2006, 15:15–19:15, P1

Spin-, energy- and timeresolved photo electron emission microscopy of 3d-transition metals — •Lutz Heyne, B Heitkamp, H. A. Dürr, and W. Eberhardt — Bessy, Berlin, Germany

Early optical pump-probe experiments[1] (tr-MOKE) indicate a breakdown of ferromagnetic order on an fs timescale after an ultra short laser pulse excitation. An intensive pump pulse heats the electronic subsystem, which interacts with the spin system and induces magnetic quenching.

For the future of magneto electronic devices it is important to understand the physics of these ultra fast processes. Our approach to this topic is to directly analyse the spin of the photoelectrons emitted by the probe beam.

Therefore we employ a photo electron emission microscope (PEEM) in combination with a spin analyser (SPLEED). Fs time resolution is obtained by a Ti:Saphier in our pump-probe setup. Analysing the spin of the emitted photoelectrons gives a direct measure of the magnetism in the sample. In combination with the PEEM a spatial resolution of 50nm can be obtained. Alternatively the dynamics of the excited electrons can be observed by time-of-flight spectroscopy using a delay line detector. Experiments on Nickel and Cobalt show a demagnetization on a sub-ps timescale, while the electronic system is still not thermalized.

[1] E. Beaurepaire et.al. Phys. Rev. Lett. 76, 4250 (1996)