Abstract
In spite of a number of theoretical predictions of interesting properties of surface magnons, observations have been severely restricted because of the smallness of the surface‐to‐volume ratio and the fact that only the magnetic resonance method has been available. In this paper, we propose theoretically a surface‐acoutic‐wave attenuation technique to observe a surface magnon with wave number equal to that of the acoustic wave. The surface acoustic wave gives a rotational motion to the lattice near the surface and induces a local deviation of the axis of magnetic anisotropy. Although shear strains responsible for the usual bulk magnon excitation vanish at the free surface, this rotational motion in anisotropic magnetic leads to the same effect as that of the rotating magnetic field in the magnetic resonance method. Thus, the surface acoustic wave can excite a surface magnon. As an example, it it shown how a surface spin‐flop instability proposed by Mills and Saslow may be easily observed in MnF2 by using this method. The attenuation coefficient in anisotropic ferromagnets with surface anisotropy is also calculated.
Published Version
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