Yttrium-iron-garnet (YIG) is an important technological material used
in microwave devices. in this paper we use dual microwave (1-4 GHz) dr
ives to study the dynamical bifurcation behavior of magnetostatic and
spin-wave modes in YIG spheres and rectangular films. The samples are
placed in a de magnetic field and driven by cw and pulse-modulated mic
rowave excitations at magnetostatic mode frequencies. A second microwa
ve drive applied to the sample excites additional spin-wave modes that
can interact with those arising from the original excitation and ther
eby affect the transmission characteristics at the primary frequency.
We find a significant decrease in transmission of the primary when the
secondary frequency is tuned to approximately half that of the primar
y drive. This decrease is observed both in the steady state behavior a
nd in the initial overshoot transient associated with pulse modulation
of the primary excitation. Results such as these are often treated by
extending linear theory to include higher order interaction terms. He
rein we present a simple dynamical model that reproduces results that
qualitatively resemble the experimental data. (C) 1997 American Instit
ute of Physics.