Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 21: Magnetic Thin Films II

MA 21.6: Talk

Wednesday, February 27, 2008, 15:15–15:30, H 1012

Mößbauer study of epitaxial Co₂Cr_0.6Fe_0.4Al thin films. — •Vadim Ksenofontov¹, Christian Herbort², Martin Jourdan², and Claudia Felser¹ — ¹Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg - University, 55099 Mainz — ²Institute of Physics, Johannes Gutenberg - University, 55099 Mainz

Epitaxial thin films of the promising for spintronic applications Heusler half-metallic compound Co₂Cr_0.6Fe_0.4Al (CCFA) were investigated using conversion electron Mößssbauer spectroscopy (CEMS) in order to get insight into the structural and magnetic properties. Thin films of 100 nm thickness were deposited by rf magnetron sputtering on MgO substrates without and with 10 nm Fe buffer layer. We discuss a correlation between the annealing temperature and the structural disorder and hyperfine fields on Fe atoms measured by Mößbauer spectroscopy. Samples prepared at the optimum annealing temperature as determined by tunneling magnetoresistance measurements show the optimum degree of order on the Fe sites as determined by CEMS. Additionally, we observed evidence for a diffusion of Cr atoms from the CCFA thin film into the Fe buffer layer and the related diffusion of Fe atoms from the buffer into the CCFA film. Thus the thermal treatment changes the Fe to Cr ratio of the Heusler compound additional to influencing the degree of disorder on the Fe/Cr sites.

The authors gratefully acknowledge financial support by the DfG (Research Unit 559).