Toggle switching of weakly coupled synthetic antiferromagnet for high-density magnetoresistive random access memory

The toggle-switching behavior for circular and elliptic cylinder shaped memory cells of weakly coupled synthetic antiferromagnet with a diameter and thickness (ferromagnetic layer) ranging from 200 to 400 and from 2.5to5.0nm, respectively, has been studied by micromagnetic simulation. The critical fields for a circular cylinder are much larger than those predicted by a single domain model. This is due to the formation of edge domains resulting in a so-called S state. The elliptic cylinder with an aspect ratio of >1.2 is found to be necessary to prevent the increase of the start field by the edge domains.