Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)
O 58.32: Poster
Mittwoch, 13. März 2013, 18:15–21:45, Poster B1
Temporal Evolution of Excited Electrons in the Ni(111) Image-Potential States — •Beatrice Andres1, Paul Weiss1, Marko Wietstruk1, Anke B. Schmidt2, Markus Donath2, and Martin Weinelt1 — 1Fachbereich Physik, Freie Universität Berlin, 14195 Berlin — 2Physikalisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster
In ferromagnetic materials electronic relaxation times differ for electrons with majority and minority spin. Besides spin-conserving decay, which mainly occurs through inelastic electron-electron scattering, relaxation is also caused by spin-flip processes. Additionally the interaction of electrons with phonons and defects give rise to spin-dependent dephasing rates.
In spin- and time-resolved two-photon-photoemission experiments (2PPE) we populate the n=1 and n=2 image-potential states on Ni(111) with the third harmonic (3hν ≈ 5.0 eV) of our Ti:Sa laser. We can excite electrons from different initial states by changing the photon energy and thus modify the spin polarization created in the image states. Probing the electronic structure after a variable time delay with the fundamental (1hν ≈ 1.67 eV) enables us to study spin-dependent differences in image-state lifetimes and temporal evolution of linewidths. Our results indicate diversities in the decay channels and dephasing processes for majority- and minority-spin electrons.