Berlin 2008 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 39: Magnetism in Thin Films: Interaction Phenomena and Heterostructures

DS 39.4: Vortrag

Freitag, 29. Februar 2008, 11:30–11:45, H 2032

Highly ordered spin-state in an epitaxial spin-valve — •Frank Brüssing, Boris Toperverg, Hartmut Zabel, and Katharina Theis-Bröhl — Department of Physics 4, Ruhr-University Bochum, D-44780 Bochum, Germany

Several periods of Fe and Co films separated by Cr layers were grown on MgO (001) by molecular beam epitaxy to form an epitaxial spin valve superlattice. We adjusted the film thicknesses of Fe and Co to have similar magnetic moments in the both magnetic layers. In order to get a proper spin-valve behavior we have chosen a Cr spacer thickness which provides a week antiferromagnetic coupling. The quality of the layering and the epitaxial relationship were verified via x-ray methods. For investigating of the arrangement of the magnetic moments in the different magnetic layers we performed polarized neutron reflectometry studies in the as-grown state and with an applied magnetic field. Ferromagnetic and antiferromagnetic alignment between neighboring Co and Fe layers can be recognized via intensity variations on the nuclear [Co/Cr/Fe/Cr] superlattice peaks which are different for odd and even orders. Interestingly, additional half-order peaks appear in the asgrown state indicating a new magnetic state. In this state an antiferromagnetic alignment between complete neighboring [Co/Cr/Fe/Cr] unit cells occurs suggesting a highly-ordered demagnetized state induced by dipolar interaction during growth. Applying a magnetic field destroys this state which also can not be recoverd during field reversal. This project was supported by the DFG via SFB491.