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MA: Fachverband Magnetismus

MA 35: Spin-Dynamics / Spin-Torque IV

MA 35.2: Vortrag

Donnerstag, 26. März 2009, 15:30–15:45, HSZ 04

Femtosecond Dynamics of Spin and Orbital Angular Momentum in Nickel — •Christian Stamm, Niko Pontius, Karsten Holldack, Torsten Quast, Torsten Kachel, Marko Wietstruk, Rolf Mitzner, and Hermann A. Dürr — Elektronenspeicherring BESSY II, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin

At the BESSY femtoslicing source we measure x-ray magnetic circular dichroism (XMCD) with 100 fs time resolution [1,2]. By virtue of the XMCD sum rules, we find that the spin and orbital momenta in a thin nickel film are quenched with a time constant of 150 fs upon excitation with a fs laser pulse. This represents the first unambiguous proof that the total electronic angular momentum is transferred to the lattice on the same ultrafast time scale. The quenching of orbital angular momentum also is a serious constraint for models of angular momentum dissipation.

[1] S. Khan et al., Phys. Rev. Lett. 97, 074801 (2006).

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