Spatial control of magnetic anisotropy for current induced domain wall injection in perpendicularly magnetized CoFeBMgO nanostructures

Magnetic anisotropy of perpendicularly magnetized CoFeBMgO films is spatially tailored using depth controlled Ar ion etching with patterned etching masks. Nanowires with patterned etching have significantly reduced coercivity compared to those without the etching. We show that the sign of the anisotropy can be locally changed by partially etching the MgO layer, and as a consequence, 90° domain walls can be created at the boundary of etched/non-etched region. Direct current application to the nanowire can result in moving such 90° domain walls, which can prove as an efficient mean to inject domain walls into perpendicularly magnetized nanowires.