REFLECTION AND SCATTERING OF SPIN-WAVES BY SURFACE-ROUGHNESS OF A FERROMAGNET

A detailed theory of volume spin wave reflection from the randomly rou gh surface of a ferromagnet is presented. The contribution to damping of the reflected wave is calculated. This contribution is due to the s cattering of the initial volume wave into secondary surface and volume spin waves. The value of damping is proportional to the correlation l ength and the square of the roughness amplitude. Numerical calculation s of the attenuation rate as a function of the angle of incidence and the ratio between the surface anisotropy and the wavenumber are provid ed. They yield the angle of incidence where the attenuation has a maxi mum. In analogy to optics, this angle is similar to the Brewster angle . Numerical estimations of damping and a comparison of its value with the ferromagnetic resonance linewidth are also made. Finally, the resu lts of the calculation of the scattering of surface exchange spin wave s by surface roughness are presented and discussed.