Parametric Effects in Magnetoacoustic Resonance

Experimental and theoretical results are presented to substantiate the parametric origin of the excitation of megacycle frequency acoustic modes in a polished YIG sphere by microwave power. A method is described for measuring the acoustic Q using a component of transverse magnetization varying at the acoustic frequency to induce a voltage in a loop placed around the sphere. The response of the magnetostatic acoustic mode system for microwave powers less than that necessary to excite the acoustic oscillation has been investigated. An equivalent circuit of the system is derived which explains the observed results.