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Phys. Rev. B 51, 2920–2929 (1995)

[Issue 5 – 1 February 1995 ]

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Strong anisotropies in MBE-grown Co/Cr(001): Ferromagnetic-resonance and magneto-optical Kerr-effect studies

F. Schreiber

Institut für Experimentalphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany

Z. Frait

Institute of Physics, Czech Academy of Sciences, 18040 Prague, Czech Republic

Th. Zeidler, N. Metoki, W. Donner, H. Zabel, and J. Pelzl

Institut für Experimentalphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany

Ferromagnetic-resonance (FMR) and magneto-optical Kerr-effect (MOKE) studies of molecular-beam-epitaxy grown Co/Cr(001) superlattices and single layers are presented. The FMR measurements were performed in different sample orientations and in a broad frequency range (9–92 GHz). MOKE hysteresis loops were detected in polar and in longitudinal configuration. The in-plane anisotropy parameters, K₁ and K₂, the out-of-plane anisotropy (i.e., the effective magnetization including the surface anisotropy, K_s), and the g factor were determined for these samples, which exhibit an anomalous out-of-plane lattice expansion of the hcp Co(112-bar0) on bcc Cr(001) as a precursor of a structural phase transition. Due to the strong in-plane anisotropy the switching of the magnetization to out-of-plane easy axis can occur at lower thicknesses ( [approx equals] 14 Å) than the change of sign of the effective magnetization ( [approx equals] 21 Å). In the intermediate thickness range a peculiar situation can be found with the orientation of the magnetization along the surface normal lying energetically between the in-plane easy and hard axis. Taking into account these effects as well as a reduced magnetic moment, K_s [approx equals] 0.76 erg/cm² is found. For thin Co layers the g factor is found to be increased in comparison with the bulk value. This indicates modifications of the electronic properties accompanied with the considerable structural changes.

©1995 The American Physical Society

URL: http://link.aps.org/abstract/PRB/v51/p2920
DOI: 10.1103/PhysRevB.51.2920
PACS: 75.30.Gw, 75.70.-i, 76.50.+g

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