Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 32: Postersession II: Spinstruct./Phase Trans. (1-10); Spinelectronics (11-15); Thin Films (16 - 36); Particles/Clusters (37-45); Multiferroics (46-54); Spindynamics/Spin Torque (55 - 76); Post Deadlines (77-79)

MA 32.66: Poster

Freitag, 29. Februar 2008, 11:15–14:00, Poster E

Femtosecond X-ray Spectroscopy on Ni — •Niko Pontius, Christian Stamm, Torsten Kachel, Marko Wietstruk, Hermann A. Dürr, and Wolfgang Eberhardt — BESSY m.b.H., Albert-Einstein-Str. 15, 12489 Berlin, Germany

We use fs x-ray pulses as a probe to investigate spin and electron dynamics of a thin Ni film that is excited by a fs laser pulse. Spin and orbital magnetic moments can be determined individually using sum rules of the x-ray magnetic circular dichroism (XMCD). In our pump-probe experiment, we unambiguously find that fs laser excitation is causing an ultrafast quenching of the spin moment, which is not compensated by a corresponding increase of orbital moment. As angular moment is conserved, we conclude that the quenched spin moment is transferred to the lattice on the fs time scale.

The experiments were performed at the BESSY Femtoslicing source. It is capable of generating x-ray pulses of about 100 fs duration with linear as well as circular polarization. The photon energies range from 400-1200 eV, allowing for x-ray absorption measurements of the 3d transition and rare-earth elements.