Significant reduction in writing field of toggle MRAMs using novel free layer structures

Abstract We have investigated the toggle writing characteristics of free layers where two soft magnetic layers (SLs) were ferromagnetically coupled with a synthetic antiferromagnet (SAF) trilayer through ferromagnetic coupling layers (FCLs). In the free layer, the soft magnetization reversal of each SL alternately induced the spin flop of the SAF trilayer at a low field and the strong antiferromagnetic coupling of the SAF trilayer maintained a high saturation field ( H s ). As the coupling strength through the FCL decreased, the spin-flop field ( H flop ) decreased and H s increased simultaneously. This can largely decrease the writing field and enlarge the writing margin in toggle MRAMs.