Asymmetric magnetization reversal of the Heusler alloy Co2FeSi as free layer in an CoFeB/MgO/Co2FeSi magnetic tunnel junction

We report the in-plane magnetization reversal behavior of Co2FeSi Heusler alloy free layer in a bottom-pinned magnetic tunnel junction film with 149% TMR. Using magneto-optic indicator imaging, we visualize domain dynamics this buried integrated within full stack. The reveal anisotropic under applied fields. While fields perpendicular to exchange bias direction indicates smooth, coherent rotation away from easy axis, asymmetric is observed along axis. Reversed domains propagate interior laterally outward toward edges as switches into parallel alignment pinned synthetic antiferromagnetic reference (IrMn/CoFe/Ru/CoFeB). On other hand, inward for transition antiparallel layer. These results have important implications device performance.