Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 90: Post-Deadline Session

O 90.4: Vortrag

Donnerstag, 3. April 2014, 20:45–21:00, TRE Phy

k-Space Mapping Within Minutes: The Anisotropic Dirac-Type Surface State on W(110) and Mo(110) — •Gerd Schönhense1, Katerina Medjanik1, Sergey Chernov1, Florian Schertz1, Sergey A. Nepijko1, Hans-Joachim Elmers1, Andreas Oelsner2, Christian Tusche3, Alexander Krasyuk3, and Jürgen Kirschner31Institut für Physik, Johannes Gutenberg-Universität, Mainz — 2Surface Concept GmbH, Mainz — 3Max Planck Institut für Mikrostrukturphysik, Halle

We present a novel method for k-space mapping of electronic bands with utmost efficiency. As model example served the highly anisotropic Dirac-type surface state recently discovered on W(110) [1] and the analogous state on Mo(110). The instrument combines the k-imaging properties of a cathode lens microscope with the superior resolution and parallel acquisition of ToF spectroscopy. We use 2PPE excitation (2hv=5.8−6.6 eV) via a TiSa femtosecond laser and a delayline detector for rapid single-event counting. The dispersion behavior of the bands is observed in a 3D (kx,ky,E) matrix, requiring only few minutes acquisition time. An integral imaging spin filter [2] yields spin resolved 3D-maps. Using s-, p- and circular polarization we probe orbital symmetries and hybridization effects of the band states, spinfiltered maps probe their spin character. As a main result we find that hole doping by oxygen shifts the Dirac state to lower binding energy. Funded by BMBF (05K12UM2 and 05K12EF1). [1] K. Miyamoto et al., PRL 108 (2012) 066808; [2] D. Kutnyakhov et al., Ultramicroscopy 130 (2013) 63

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