Abstract: Interfacial effects on ferromagnetic resonance: MBE iron films

Abstract

Recent studies have implied that the elastic strain and either the magnetization, M or the uniaxial magnetic anisotropy field HA were spatially dependent near the substrate/Fe interface. We now report additional experimental and calculational results which give further evidence for the existence of magnetic parameter variations near the interface. The experimental program consisted of ferromagnetic resonance (FMR) experiments as a function of frequency (9, 16, and 35 GHz), magnetic field direction (parallel and perpendicular to the film plane), and film thickness (t=500–5000 Å). The FMR experiments were complemented with magnetometer measurements. The calculations consisted of determining both volume and surface spin wave dispersions as a function of various assumed variations of magnetic parameters near the interface. This allowed us to predict the excitation of surface modes besides the usual volume spin wave modes. Experimentally, surface modes are excited for t≳1000 Å and are displaced about 500–1000 Oe above the main line. In addition we were able to predict the deviation from quadratic behavior for low order number spin wave excitations as corroborated experimentally. It may now be meaningful to determine intrinsic magnetic properties of both the substrate/Fe and the Fe/air surfaces.