Normal modes of magnetic domain wall motion in a confined stripe domain lattice

Abstract

We report the observation of standing wave modes in an array of stripe domains confined by a pair of parallel cracks in a Gd, Ga:YIG film. These modes appear in the response spectrum of the confined lattice as shallow minima or maxima at frequencies lower than that of the usual domain wall resonance peak. A simple model, analogous to the forced response of a membrane clamped at the edges, fits the spatial patterns of wall motion observed at the frequencies of the maxima and minima. Experimental frequency-wave vector values, interpreted with guidance from this analogy, provide the first experimental dispersion curve for a stripe domain lattice. We compare this result with recent theoretical calculations. The experimental value of the uniform mode frequency is 41.5 ± 0.2 MHz, with a long wavelength group velocity of 330±50 m/sec. A surprising conclusion from the observed extrema of the spatial patterns is that the damping of the waves is an order of magnitude less than expected from the damping of the uniform mode. The estimated decay length for a propagating wave is 400 μ.