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 35.74: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster B

Using a two-dimensional electron mirror for efficient spin-resolved bandstructure mapping — •Christian Tusche, Martin Ellguth, Aimo Winkelmann, Alexander Krasyuk, and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany

We measure the spin-polarization of photoelectrons emitted from several atomic layers thick Co films grown on Cu(100) using a momentum microscope. This instrument, consisting of a photoemission electron microscope (PEEM) and an aberration corrected electrostatic energy analyzer directly records the parallel momentum component, k_||, of photoelectrons emitted from the sample. Spin-filtering is based on the diffraction of low energy electrons in the (00)-LEED spot of a W(100) crystal, installed at the exit of the energy filter. In the spatial imaging mode, PEEM images of the magnetic domain structure of the Co films showed that 3800 image points can be recorded simultaneously [1].

A series of constant-energy cuts through the Brillouin zone gives direct access to the valence band electronic structure of the ultra-thin Co-film. By inserting the W(100) electron mirror into the electron optical path, the spin-resolved distribution of photoelectrons as a function of k_||(x,y) is recorded simultaneously with unprecedented efficiency. By exploiting the energy dependent spin-sensitivity of the low energy diffraction process, the absolute value of the spin-polarization can be obtained without magnetization reversal of the sample.

[1] Tusche, Ellguth, Ünal, Chiang, Winkelmann, Krasyuk, Hahn, Schönhense and Kirschner, Appl. Phys. Lett. 99, 032505 (2011)