Analysis of Magnetoelastic Conversion Efficiency

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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.