COLLECTIVE SPIN-WAVES IN AN ULTRATHIN FE WEDGE - A BRILLOUIN-SCATTERING STUDY

Collective spin waves in an ultrathin epitaxial bcc Fe(001) wedge with a maximum thickness of 8.9 Angstrom have been investigated using Bril louin scattering at room temperature. Observation of well-defined spin -wave peaks for Fe thickness d = 2.6 Angstrom confirmed a stable ferro magnetic order at room temperature. Spin wave frequencies were determi ned as a function of the external magnetic field up to 4.5 kOe for Fe thicknesses, 2.6, 3.9, 6.5 and 8.9 Angstrom, from which the saturation magnetization, g-factor, and surface magnetic anisotropy constants ha ve been determined. With decreasing the Fe thickness, the saturation m agnetization gradually decreases from 21.0 kG at 8.9 Angstrom to 18.6 kG at 2.6 Angstrom. We also found that the stable direction of the mag netization of the wedge under zero magnetic field turns over from the in-plane direction to the surface normal below d approximate to 3 Angs trom due to the competition between the out-of-plane surface magnetic anisotropy and the in-plane shape magnetic anisotropy.