Time domain MOKE detection of spin wave modes and precession control for magnetization switching in ferrite films

The dynamic magnetization response to pulse fields for magnetic garnet films was measured by time-resolved magneto-optical Kerr effect techniques. A damped precession, or ringing, is found when the pulse is turned on or off. The ringing amplitude after turn off shows alternating maxima and minima as the static field is changed. A fast Fourier transform analysis gives peaks at frequencies which match those expected from ferromagnetic and spin wave resonance for fields above 25 Oe. Lower frequency modes indicative of surface anisotropy are also found. The change in intensity with field for the two strongest peaks tracks the variation in the ringing amplitude.