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DS: Fachverband Dünne Schichten

DS 40: Magnetism in Thin Films: Interaction Phenomena and Heterostructures

DS 40.6: Vortrag

Freitag, 29. Februar 2008, 14:00–14:15, H 2032

Magnetism of the Heusler compound Co₂Cr_0.6Fe_0.4Al at interfaces with Cr and AlO_x — •Martin Jourdan¹, Elena Arbelo-Jorge¹, Christian Herbort¹, Timothy Charlton², and Sean Langridge² — ¹Institut für Physik, Johannes Gutenberg Universität Mainz, 55099 Mainz, Germany — ²ISIS facility, Rutherford Appleton Laboratory, Oxfordshire OX11 0QX, UK

Co₂Cr_0.6Fe_0.4Al (CCFA) belongs to the Heusler compounds for which a huge spin polarization is theoretically predicted. However, for spintronics applications the electronic properties at the interface with insulating barriers (tunneling devices) or paramagnetic metals (spin valves) are of major importance.

We investigate the ferromagnetic moment of CCFA at interfaces with Cr and AlO_x by polarised neutron reflectometry (PNR). Fitting the reflectometry data to a model which allows layers of the CCFA with different magnetic moments compared to the bulk moment, evidence for a reduced moment in a 1-2nm interface layer of the CCFA was identified. However, the reduction is clearly smaller at the Cr interface compared to the AlO_x interface.

Additionally, at the Cr interface the best fits are obtained, if ferromagnetic order of the complete 6nm Cr layer is assumed (with ≃ 0.3 µ_B /Cr-atom). This surprising observation is discussed in the framework of epitaxially induced stress of the Cr layer.