Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 13: Poster Ia: Electron Theory (1); Magnetic Imaging (2,3); Thin Films (4-25); MSMA (26-33); Magn. Semiconductors (34-42); Magn. Half Metals and Oxides (43-60)

MA 13.52: Poster

Dienstag, 24. März 2009, 10:15–13:00, P1A

X-ray absorption spectroscopy of half-metallic Co₂TiZ (Z = Si, Ge and Sn) — •Peter Klaer¹, Michael Kallmayer¹, Thorsten Methfessel¹, Hans Joachim Elmers¹, Benjamin Balke², Joachim Barth², Tanja Graf², Gerhard Fecher², and Claudia Felser² — ¹Institut für Physik, Johannes Gutenberg-Universität Mainz, D-55128 Mainz, Germany — ²Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany

X-ray magnetic circular dichroism (XMCD) of core-level absorption spectra has been measured for the Heusler alloys Co₂TiZ (Z = Si, Ge, Sn and Sb) at the L_{3, 2}-edge. Half-metallic properties have been predicted for Z = Si, Ge and Sn. Co₂TiZ samples were prepared by arc melting of stoichometric quantities of the constituents. Bulk samples were in situ cleaved, shortly before data acquisition, to guarantee a clean surface. We have determined the element specific spin and orbital magnetic moments from the XMCD spectrum using a sum rule analysyis. Results are compared with data from SQUID magnetometry and theory. Co and Ti show antiparallel magnetic spin moments, except for the compound containing Sb. This means that Co₂TiZ (Z = Si, Ge, Sn) is a ferrimagnet, in agreement with theory. Assuming, that the x-ray absorption spectra at the L₃-edge is proportional to the spin density of states (DOS), we calculated the spin resolved DOS function from the experimental XMCD spectra. These results are in agreement with the predicted band structure of these materials. We also show atomically resolved STM images of the cleaved surfaces.