Magnetoelastic Waves in Time-Varying Magnetic Fields. II. Experiments

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Abstract
Experiments which confirm the theoretical predictions on the propagation of magnetoelastic waves in time varying magnetic fields are described. Frequency shifts of spin waves as high as 1 GHz have been observed at L‐band microwave frequencies, in axially magnetized rods of yttrium iron garnet (YIG). Experiments with magnetoelastic pulses were performed in cases where the signal is injected either as a phonon (piezoelectric excitation) or as a magnon (fine‐wire excitation). The first demonstrates frequency conversion and group velocity modulation. The latter scheme is suitable to observe pulse compression and expansion due to frequency modulation and time changes of the group velocity. It is also used to ``trap'' magnetoelastic pulses in the phonon state, by removal of the crossover point.