Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 43: Poster Session II - MA 141/144 (Surface Spectroscopy on Kondo Systems; Frontiers of Surface Sensitive Electron Microscopy; Methods: Scanning Probe Techniques+Electronic Structure Theory+Other; Time-Resolved Spectroscopy of Surface Dynamics with EUV and XUV Radiation; joined by SYNF posters)

O 43.5: Poster

Tuesday, February 26, 2008, 18:30–19:30, Poster F

Optical magnetic circular dichroism in two-photon photoemission — •Kerstin Hild, Jochen Maul, Gerd Schoenhense, and Hans-Joachim Elmers — Institut fuer Physik, Staudinger Weg 7, Johannes Gutenberg-Universitaet, D-55128 Mainz

Magnetic circular dichroism in two-photon photoemission (2PPE) was demonstrated based on frequency-doubled femtosecond laserlight (pulse length ~150fs). Thin films of Ni2MnGa and Co2FeSi Heusler alloys showed magnetic asymmetries in the integrated photoemission intensity of 0.35% and 0.43%. Thereby, 2PPE was excited by perpendicular incident polarization-modulated light, while the sample magnetization was orientated parallel and antiparallel to the laser beam by an external magnetic field. Asymmetries were measured by a phase-sensitive detection. Furthermore a magnetite thin film was investigated by frequency-tripled laser light in one-photon photoemission showing a magnetic asymmetry of 0.47%, which is much larger than the value 0.08% measured under two-photon-photoemission. The results are compared with earlier work using linearly polarized UV light [1] and circularly polarized laser light [2].

[1] G.K.L. Marx, H.J. Elmers, G. Schönhense, Phys. Rev. Lett. 84 (2000) 5888. [2] T. Nakagawa, T. Yokoyama, Phys. Rev. Lett. 96 (2006) 237402.