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MA: Magnetismus

MA 4: Magnetic Materials I

MA 4.5: Vortrag

Montag, 27. März 2006, 11:15–11:30, HSZ 401

Bulk sensitive photoemission spectroscopy of the quaternary Heusler alloy Co₂Cr_0.6Fe_0.4Al. — •Sabine Wurmehl¹, Gerhard H. Fecher¹, Kristian Kroth¹, Florian Kronast², Hermann A. Dürr², Yukiharu Takeda³, Yuji Saitoh³, Keisuke Kobayashi^3,4, Gerd Schönhense¹, and Claudia Felser¹ — ¹Johannes Gutenberg-Universität, 55099 Mainz, Germany — ²BESSY, 12489 Berlin, Germany — ³Spring-8 / JAERI, Hyogo, 679-5198, Japan — ⁴Spring-8 / JASRI, Hyogo, 679-5198, Japan

Quaternary Heusler alloy Co₂Cr_0.6Fe_0.4Al was investigated experimentally and theoretically. The electronic structure and spectroscopic properties were calculated using the full relativistic Korringa-Kohn-Rostocker method with coherent potential approximation to account for the random distribution of Cr and Fe atoms as well as random disorder.

Resonant (560eV - 800eV) soft X-ray as well as high resolution - high energy (3.5keV, 8keV) hard X-ray photoemission was used to probe the density of the occupied states in Co₂Cr_0.6Fe_0.4Al. It was found by resonant and high energy photoemission that there is a discrepancy between the experimentally observed and the theoretically calculated density of states in Co₂Cr_0.6Fe_0.4Al. This observation suggests the presence of correlation in Heusler compounds being not accounted for by local (spin) density approximation in its current form. Moreover, strong differences in surface and bulk photoemission spectra reveal the loss of the bulk and structure signature if emission takes mainly place from the surface layer. (This work is funded by the DFG in FG 559.)