Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 33: Magnetization Dynamics I of 3

MA 33.9: Vortrag

Donnerstag, 14. März 2013, 11:30–11:45, H22

Ultrafast loss of the classical magnetization — •Andreas Fognini¹, Gerard Salvatella¹, Florian Sorgenfrei², Martina Dell'Angela³, Martin Beye², Florian Hieke³, Dima Kutnyakhov⁴, Pavel Lushchyk⁴, Andrea Eschenlohr², Sanne de Jong⁵, Roopali Kukreja⁵, Natalia Gerasimova⁶, Harald Redlin⁶, Joerg Raabe⁷, Andreas Oelsner⁸, Christian Stamm², Urs Ramsperger¹, Joachim Stöhr⁵, Hermann Dürr⁵, Alexander Föhlisch², Wilfried Wurth³, Gerd Schönhense⁴, Andreas Vaterlaus¹, Thomas Michlmayr¹, and Yves Acremann¹ — ¹ETH Zürich, Schweiz — ²HZB Berlin, Deutschland — ³Uni. Hamburg, Deutschland — ⁴Uni. Mainz, Deutschland — ⁵SLAC, Stanford, USA — ⁶DESY, Hamburg, Deutschland — ⁷PSI, Villigen, Schweiz — ⁸Surface Concept GmbH, Mainz, Deutschland

If a ferromagnet is exposed to an ultrafast laser pulse its magnetization can be reduced within less than a picosecond. Most detection schemes for the magnetization focus on electrons close to the Fermi energy or the density of empty states. The *classical* magnetization (the average spin polarization of the whole valence band) is difficult to detect. Here we present a method based on spin and time resolved photoemission using free electron laser radiation. A femtosecond 800nm laser pulse excites an Iron film. Vacuum ultraviolet pulses from the free electron laser FLASH in Hamburg extract polarized photoelectrons. Their spin polarization is detected by a Mott polarimeter as well as a novel spin analyzer based on specular reflection of an Ir crystal. We can confirm a loss of the *classical* magnetization on a sub-picosecond time scale.