Spin wave non-reciprocity and beating in permalloy by the time-resolved magneto-optical Kerr effect

We studied the propagation characteristics of spin wave modes in a permalloy stripe by time-resolved magneto-optical Kerr effect techniques. We observed a beating interference pattern in the time domain under the influence of an electrical square pulse excitation at the centre of the stripe. We also probed the non-reciprocal behaviour of propagating spin waves with a dependence on the external magnetic field. Spatial dependence studies showed that localized edge mode spin waves have a lower frequency than the spin waves at the centre of the stripe, due to the varying magnetization vector across the width of the stripe.