Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 48: Electronic Structure: Surface Magnetism and Spin Phenomena

O 48.9: Poster

Dienstag, 8. März 2016, 18:15–20:30, Poster E

Correlation effects in the surface electronic structure of Fe(110) — •Beatrice Andres, Marko Wietstruk, and Martin Weinelt — Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin

Beyond one-electron mean-field theories, electronic band energies are renormalized by many-body effects. Such a renormalization can directly be observed in photoemission as a kink in the band dispersion, where the band reaches the excitation energy of a quasi particle. In laser photoemission (hν = 6.2 eV) on Fe/W(110) we find an occupied surface band crossing the Fermi level at ∼ 0.1 Å⁻¹ in Γ-H direction. We observe a pronounced energy renormalization in this iron minority-spin surface state at 160 meV binding energy. Following Ref. [1], we assign this to a renormalization by magnon dressing of the surface electrons.

Applying spin-resolved photoemission, we are able to track the spin polarization of the surface band and ensure that the observed kink is not a trivial crossing of two bands. Our spin detection is based on exchange scattering at a magnetized Fe/W(001) target. By switching the magnetization of sample and scattering target separately, we are able to distinguish between spin polarization and dichroic effects in the photoemission process. Thereby, we find the magnetic-linear-dichroic contrast changing sign crossing the kink as expected for spin-momentum coupling.

[1] Jörg Schäfer, Phys. Rev. Lett. 92, 097205 (2004)