Evaluation of Edge Domains in Giant Magnetoresistive Junctions

We demonstrate that the spin-Seebeck effect can be used to estimate the volume of edge domains formed in a giant magnetoresistive (GMR) device. The thermal gradient induced by Joule heating can be harnessed by the addition of a ferromagnetically insulating channel of Fe2O3 on the sides of the GMR pillar. This generates a spin wave in the Fe2O3 which couples with the free-layer edge magnetisation and controls the reversal of the ferromagnetic layers in one direction only, increasing current density from (1.1±0.1)x107 A/cm2 to (7.0±0.5)x107 A/cm2. By simple assumption, we estimate the effect of the edge domain on magnetisation reversal to be (10-15)% by spin-transfer torque.