Fundamental Magnetoelastic Waves in a Thin Conductive Magnetostrictive Slab

Magnetoelastic waves (MEWs) propagating in a thin conductive magnetostrictive slab were investigated theoretically, taking account of micro-eddy current contributions. The analysis was performed under the assumption that the medium is amorphous (isotropic elasticity) but has a uniaxial magnetic anisotropy in the slab plane. For such a medium, MEWs appear in three fundamental modes: a Lamb-type wave of the extensional mode (EMEW), an SH-type wave (SMEW), and a Lamb-type wave of the flexural mode (FMEW). Micro-eddy currents crucially affected their propagation properties, thereby increasing propagation losses as well as decreasing controllability of the MEW velocity. The values of these quantities which depend strongly on the in-plane anisotropy orientation, ß, differ from the above three wave modes, because the degree of coupling between the magnetization and the lattice through magnetoelastic interaction is different for each mode. The present analysis revealed that the SMEW with ß = 45° is best suited to delay line applications.