Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 52: Time-Resolved Spectroscopy III

O 52.1: Talk

Wednesday, February 27, 2008, 15:15–15:30, MA 042

Interferometric control of spin-polarized photoemission from Cu(001) — •Aimo Winkelmann, Wen-Chin Lin, and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle(Saale), Germany

We demonstrate that we can tune the spin-polarization of photoelectrons emitted in a three-photon process from Cu(001) by interferometric control of the delay between two ultrashort optical pulses in a pump-probe experiment. As a function of pulse delay, the spin polarization can be changed from ± 20 % to ∓ 40% using circularly polarized light for excitation. We differentiate between the regime of optical interference for overlapping pulses and, for longer delays, the influence of the material response. The influence of the coherent material response is detected by observing interference oscillations at twice the optical frequency. These are created by the interference of the pump pulse induced electromagnetic polarization at the surface and the subsequent probe pulse. The spin polarization of the observed electrons for delays longer than the pulse length also shows the oscillations at twice the optical frequency.