Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 15: Magnetic Half-metals and Oxides I

MA 15.2: Vortrag

Mittwoch, 24. März 2010, 10:30–10:45, H22

XMCD as a probe for spin-orbit interaction and spin-resolved electronic structure of Heusler compounds — •Peter Klaer¹, Michael Kallmayer¹, Elena Arbelo Jorge¹, Christian Herbort¹, Gerhard Jakob¹, Martin Jourdan¹, Christian Blum², Tanja Graf², Benjamin Balke², Gerhard Horst Fecher², Claudia Felser², and Hans Joachim Elmers¹ — ¹Institut für Physik, Johannes Gutenberg-Universität Mainz, D-55128 Mainz — ²Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität Mainz, D-55128 Mainz

To confirm theoretical predictions and optimize material properties of half-metallic Heusler alloys a characterization of the electronic structure is necessary. For this purpose x-ray magnetic circular dicroism (XMCD) is a powerful tool. In addition to the element-specific determination of the spin and orbital moment, XMCD allows a direct experimental observation of the spin-resolved unoccupied density of states (DOS) in Heusler alloys. It is shown that a substitution of Ge by Ga in alloys like Co2MnGe shifts the minority DOS maximum with respect to E_F, indicating half-metallic ferromagnetism for the whole series and satisfying the rigid-band like behavior. Results for polycrystalline bulk samples and single crystalline films are discussed. We report on the orbital to spin moment ratio versus composition, relating its variation to the symmetry of the unit cell. For the series Co2Ti1-xMnxGe the Fermi energy shifts opposite to the expected rigid band behavior, which can be explained by a charge transfer from the light 3d-element Ti with antiparallel moment to Co states.