抄録
Love-type magneto-surface acoustic waves (MSAW) propagated in multilayer sputtered magnetic films have been investigated. The film structure constructs of a stack of alternate amorphous (a-)FeB films and thin SiN (or SiOx) insulating layers, that is, (a-FeB/SiN(SiOx))×n (where n is the stacking number) were deposited successively by a multitarget rf-magnetron sputtering apparatus on sodalime glass substrates. The MSAW properties were measured with a fully digitalized system controlled by a microcomputer, which allows high-resolution measurement of the phase retardation between input and output signals in the accuracy of 1 ppm. We found that the MSAW amplitude fluctuates with the bias magnetic field. This fluctuation is explained in terms of interference caused by a phase velocity change due to the local variation in the demagnetizing field, and can be eliminated by narrowing the propagation channel. The controllable phase retardation with field Δφmax increases as n is increased; Δφmax of a film with n =20 may reach up to as large as 3000 [deg./cm].
