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MA: Magnetismus

MA 20: Magnetische dünne Schichten II

MA 20.4: Vortrag

Donnerstag, 11. März 2004, 11:00–11:15, H10

Temperature-dependent magnetotransport measurements of epitaxial Fe/Cr/Fe systems with antiferromagnetic interlayer coupling — •Matthias Buchmeier, Michael Breidbach, Henning Dassow, Daniel E. Bürgler, and Peter Grünberg — Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich

We have prepared epitaxial Fe/Cr/Fe trilayers with antiferromagnetic interlayer coupling on an Au(001)/GaAs(001) buffer-system. Lithographically patterned thin stripes are characterized by current-in-plane magnetoresistance (CIP-MR) measurements, for which the magnitude as well as the in-plane direction of the external magnetic field are swept. The temperature dependence (4–270 K) of the in-plane anisotropy, the interlayer exchange coupling, and the giant and anisotropic magnetoresistance (GMR and AMR) are quantitatively determined by simultaneously fitting the angular and field dependence of the MR curves. The experimental curves are nicely reproduced within a single domain model including fourfold magnetocrystalline anisotropy and bilinear and biquadratic coupling terms for temperatures above 50 K. Below 50 K, however, we observe an anomaly which can be interpreted as an exchange bias (EB) effect with an exchange anisotropy of the order of 5 mT. Possible origins for the appearance of EB is a paramagnet-antiferromagnet phase transition of the Cr spacer or an Fe-oxide layer on top of the uncapped sample with a thickness of approximately 1 nm as determined by X-ray scattering.