The existence of uniaxial magnetic surface anisotropy in Permalloy films has been deduced by comparing the theoretical and experimental spin-wave-resonance spectra of several films with different thicknesses. The anisotropy decreases as the film thickness decreases and, for the thinnest film, becomes comparable to that given by Néel's theory (+0.08 erg/${\mathrm{cm}}^2$).

• Received 31 May 1973

DOI:https://doi.org/10.1103/PhysRevB.8.3247