AVS 49th International Symposium
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI-TuP

Paper MI-TuP3
Dynamic and Static Measurements on Epitaxial Fe/Si/Fe

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Aspects of Magnetism
Presenter: B.K. Kuanr, University of Colorado at Colorado Springs
Authors: B.K. Kuanr, University of Colorado at Colorado Springs
M. Buchmeier, Forschungszentrum Juelich GmbH, Germany
Z. Celinski, University of Colorado at Colorado Springs
R.E. Camley, University of Colorado at Colorado Springs
Correspondent: Click to Email
Strong antiferromagnetic interlayer exchange coupling across an insulating spacer is in increasing demand for high-density magnetic recording. For example such structures can be used as artificial antiferromagnets in spin valves. We report here the interlayer exchange coupling of epitaxial Fe(10 nm)/Si(t)/Fe(8 nm) trilayers as a function of Si thickness studied by Ferromagnetic Resonance (FMR), Brillouin Light Scattering (BLS) and Magneto Optic Kerr Effect (MOKE) measurement techniques. A very strong antiferromagnetic (AFM) interlayer exchange coupling (>6 mJ/cm@super 2@) was observed at a spacer Si thickness of 0.7 nm. The bilinear J@sub 1@ and biquadratic J@sub 2@ coupling constants are determined from (i) the fitting of the angular variation of the resonance field (H@sub res@) from FMR (ii) the field variation of the frequencies for the Damon-Eshbach (DE) surface modes (both optic and acoustic with non-zero k) and (iii) the fitting of longitudinal MOKE hysteresis loops. We obtain a higher H@sub res@ along the easy-axis than along the hard-axis and the magnetizations of the two Fe films are canted. The eight-fold like symmetry of H@sub res@ as a function of the angle observed at room temperature, is due to the competition between the four-fold anisotropy and AFM interfacial coupling energy. This behavior vanishes at 24 K due to a strong increase of AFM coupling in comparison to four-fold anisotropy. From the fitting of temperature variation of H@sub res@ curves, we obtain the temperature variation of the bilinear and biquadratic exchange coupling constants. This strong coupling can be related to the highly resistive Si spacer between epitaxial Fe layers.