DYNAMICS OF TRANSIENTS IN YTTRIUM-IRON-GARNET

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.