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 Fe2O3, which couples with the free-layer edge magnetization and controls the reversal of the ferromagnetic layers in one direction only, increasing the current density from ( 1.1 ± 0.1 ) ×107 A/cm2 to ( 7.0 ± 0.5 ) × 10 7 A/cm2. By simple assumption, we estimate the effect of the edge domain on magnetization reversal to be 10%–15% by spin-transfer torque.