Dresden 2003 – scientific programme

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MA: Magnetismus

MA 29: Mikro- und nanostrukturierte Materialien II

MA 29.9: Talk

Friday, March 28, 2003, 12:45–13:00, HSZ/03

Element Specific Spectromicroscopy of the Magnetoresistive Heusler Alloy Co₂Cr_0.6Fe_0.4Al — •Bernd Heitkamp¹, F. Kronast¹, H. A. Durr¹, W. Eberhardt¹, C. Felser², D. Schmitz³, and St. Cramm⁴ — ¹BESSY Gmbh, Albert-Einstein-Strass 15, 12489 Berlin — ²Universitaet Mainz, Duesbergweg 10-14, 55099 Mainz — ³Hahn-Meitner-Institut Berlin GmbH, Glienicker Strasse 100, 14109 Berlin — ⁴Forschungszentrum Juelich, IFF, 52425 Juelich

Materials displaying large changes in resistivity in response to an applied magnetic field are currently at the focus of a large scientific interest. Recently Felser et al. [1] guided by the characteristic features in the electronic structure of manganites prepared the half metallic Heusler compound Co₂Cr_0.6Fe_0.4Al and found a large nearly temperature independent magnetoresistance of 24% in a relatively low magnetic field of up to 0.1T. Although of tremendous importance for spintronics applications the microscopic origin of the large magnetoresistance in these materials is poorly understood. Particularly intriguing are the soft magnetic properties of the compounds. We used magnetic circular x-ray dichroism to image the magnetic domain structure element specifically with photoemission electron microscopy. Spectromicroscopy allowed us to obtain laterally resolved maps of orbital and spin magnetic moments. We show that the magnetic properties depend sensitively on the sample stoichiometry and surface preparation.

[1] T. Block et al., submitted to Appl. Phys. Lett. (2002)