Higher-Order Spin-Wave Instability Excited by Parallel Pumping

Abstract

The parametric excitation of spin waves has been investigated theoretically without using the conventionally adopted approximation of neglecting those terms in the equations of motion that lead to the excitation of nonresonant components of the magnetization. The usually neglected terms generate instabilities of higher order in which the resonant frequency of the unstable spin waves equals an integer multiple of half the pump frequency. These higher-order instabilities should become observable if the dc magnetic field is high enough to suppress the lower-order instabilities.