Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)
O 35.70: Poster
Dienstag, 27. März 2012, 18:15–21:45, Poster B
Investigation of ultrathin Fe films on Ag(001) using linear and nonlinear photoemission — •Thiago Peixoto1, Mariusz Pazgan1, Francesco Bisio1,2, Aimo Winkelmann1, Maciej Dabrowski1, Marek Przybylski1, and Jürgen Kirschner1 — 1MPI of Microstructure Physics, Halle-Saale, Germany — 2CNR-SPIN, Genova, Italy
Investigations of iron films grown on silver surfaces have shown an intriguing thickness-dependent oscillatory magnetic anisotropy [1,2]. This behaviour was explained by the appearance of quantum well states (QWS) in the Fe film. In order to access the relevant electronic states, we investigated ultrathin Fe/Ag(001) films by angle- and spin-resolved one-photon (1PPE, hν=6 eV) and multi-photon photoemission (2PPE, 3PPE, hν=3 eV) at 150 K. Consistent with the observation of 5.6 ML oscillations of QWS in Fe/Ag(001) [2], we report periodic thickness- and energy-dependent intensity variations of electronic transitions in 1PPE and 2PPE spectra. Using different incident light polarizations, we identify the presence of specific unoccupied states in 2PPE. The Fe films show an average spin-polarization of about 30% near EF in 2PPE and 10% in 1PPE. This difference is attributed to the influence of unoccupied states. By means of angle-dependent 3PPE, the n=1 image-potential state of Fe/Ag(001) is identified, with an estimated electron effective mass of meff=0.75me and a binding energy of EB=0.77 eV with respect to the vacuum level.
[1] U. Bauer and M. Przybylski, Phys. Rev. B 81, 134428 (2010).
[2] J. Li et al., IEEE Trans. Magn. 47, 1603 (2011).