Influence of the nature of the interface on the spin wave resonance spectra of single-crystal nickel films

Abstract

Observations and associated analyses of the microwave resonance absorption of single-crystal nickel films are described in this paper. NaF films evaporated prior to and/or after nickel deposited onto various crystalline substrates were used to investigate the nature of the asymmetries in several nickel interfaces prepared under various deposition conditions by means of spin wave resonance (SWR) experiments. The angular dependence of SWR spectra obtained for some films provides evidence for the existence of quasi-localized surface (QLS) modes lying within those of the bulk mode manifold. The QLS mode transforms into an acoustic surface mode as the magnitude of the surface pinning parameter is changed. The results also indicate that while the acoustic surface mode disappears from the spectrum at a certain angle, the QLS mode first transforms to an acoustic surface mode and then disappears at a larger angle. All this occurs as the static magnetic field is rotated from the perpendicular to parallel orientation with respect to the film normal. These observations are consistent with the predictions given by Puszkarski's models (H. Puszkarski, Prog. Surf. Sci., 9 (1979) 191; Solid State Commun., 33 (1980) 757). The effect of stress on the SWR spectra indicates that, for the same film, the number of resonance modes and their intensities in strain-free films are less than in strained films. This feature suggests that pinning at the film-substrate interface dominates over that at the film-air interface.