Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 14: Spin Dynamics / Spin Torque I

MA 14.10: Vortrag

Mittwoch, 24. März 2010, 12:00–12:15, H10

Enhanced Spin-Orbit Interaction During Ultrafast Demagnetization of Nickel — •Christian Stamm, Niko Pontius, Torsten Kachel, Marko Wietstruk, and Hermann A. Dürr — Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronenspeicherring BESSY II, Albert-Einstein-Str. 15, 12489 Berlin

Time-resolved x-ray absorption spectroscopy (XAS) allows for a detailed view of microscopic processes during ultrafast demagnetization following a laser pump pulse. Previously we have shown that both spin and orbital angular momentum are quenched within a few 100 fs, utilizing the x-ray magnetic circular dichroism (XMCD) sum rules [1]. In addition, XAS is able to measure the spin-orbit interaction by quantifying the absorption ratio between the spin-orbit split L3, L2 absorption edges, the so-called branching ratio [2]. We find an increase of the spin-orbit coupling just after laser excitation, which persists during the demagnetization process. This is the first experimental demonstration of laser-enhanced spin-orbit interaction.

[1] C. Stamm et al., Nature Mater. 6, 740 (2007).

[2] G. van der Laan, B. T. Thole, Phys. Rev. Lett. 60, 1977 (1988).