Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 21: Magnetic Thin Films II

MA 21.10: Vortrag

Mittwoch, 27. Februar 2008, 16:30–16:45, H 1012

Uniaxial magnetic anisotropy of Fe_1−xCo_x(110) /GaAs(110) and Fe_1−xCo_x(001)/GaAs(001) — •Björn Muermann, Florian Nitsch, and Günther Bayreuther — Universität Regensburg, Germany

The tailoring of the magnetic properties of ferromagnets on semiconductors is of prime importance to the field of spintronics. In this contribution we have compared the magnetic anisotropy of epitaxial Fe_1−xCo_x(110) and Fe_1−xCo_x(001) (0≤ x≤ 0.8) films grown by MBE on GaAs. The samples were studied by means of AGM and FMR spectroscopy. The angular dependent energy density observed can be explained by two main contributions to the magnetic anisotropy: an effective fourth order anisotropy, K₁^eff(t), and an effective second order anisotropy, K_U^eff(t). The fourth order term originates from the cubic symmetry of the bcc FeCo lattice. The thickness dependence of K₁ is in good agreement with the prediction for the sign reversal according to Néel’s pair energy model [1].

The uniaxial anisotropy of FeCo alloys on GaAs(001) has been found to be independent of composition and to be a pure interface phenomenon arising from the bonding mechanism of the Fe/Co atoms to the As atoms [2]. For (110)-oriented films one observes an opposite sign of K_U for Fe-rich and Co-rich alloys exactly as for K₁. It is concluded that for (110)-oriented FeCo films the uniaxial anisotropy is mainly of magneto elastic origin.

[1] G. Bayreuther et al., J. Appl. Phys. 93 (2003) 8230,

[2] M. Dumm et al., J. Appl. Phys. 91 (2002) 8763