Absorbing boundary layers for spin wave micromagnetics

Micromagnetic simulations are used to investigate the effects of different absorbing boundary layers(ABLs) on spin waves (SWs) reflected from the edges of a magnetic nano-structure. We define the condi-tions that a suitable ABL must fulfill and compare the performance of abrupt, linear, polynomial and tanhyperbolic damping profiles in the ABL. We first consider normal incidence in a permalloy stripe and pro-pose a transmission line model to quantify reflections and calculate the loss introduced into the stripedue to the ABL. We find that a parabolic damping profile absorbs the SW energy efficiently and has alow reflection coefficient, thus performing much better than the commonly used abrupt damping profile.We then investigated SWs that are obliquely incident at 26.6; 45 and 63.4 on the edge of a yttrium-iron-garnet film. The parabolic damping profile again performs efficiently by showing a high SW energytransfer to the ABL and a low reflected SW amplitude.