Propagation of Magnetostatic Spin Waves at Microwave Frequencies in a Normally-Magnetized Disk

Abstract

The theoretical transit time is derived for propagation of spin waves across a normally-magnetized disk. The exchange-free case is described first. The group velocity is obtained for magnetostatic spin waves in an infinite slab. This is combined with the inhomogeneous internal field of a disk to compute the time delay of a wave packet in the disk. The time delay obtained from a computer calculation is compared with an approximate calculation. The dispersion relation is then modified to include exchange effects and the delay time is computed for this case. Experimental observations of microwave pulse-echo behavior in disks of yttrium iron garnet are compared with these theoretical results.