Analysis of Magnetoelastic Conversion Efficiency

Abstract

Coupling of spin waves and elastic waves in ferrimagnetic materials is investigated theoretically. The magnetoelastic equations are transformed into coupled equations for fast and slow hybrid waves; the magnetoelastic coupling mechanism is then treated as a distributed directional coupler where the velocities of quasinormal modes are slowly tapered over the coupling length. Solution of the hybrid wave equations using a computerized numerical integration yielded conversion efficiencies versus magnetic field gradient. Over the efficiency range from 10% to 99.4% the conversion efficiency is equal to 1 − exp (−H′_crit/ |H′|), to within one‐half of one percent. The results provide a complete curve of conversion efficiency versus field gradient, and at the limits agree with Schlömann's strong and weak coupling approximations.