Modulation of Asymmetric Magnetic Domain-Wall Motion via Noncolinear Interlayer Exchange Coupling

The search of scalable approach to design field-free deterministic switching is currently a key challenge. Here, we investigate current and magnetic driven magnetization switching in a T-type magnetic heterojunction with a structure composed by a hybrid synthetic antiferromagnet (SAF) Co/Ta/CoTb/Pt, where the bottom Co layer has in-plane magnetic anisotropy (IMA) and the top CoTb layer has perpendicular magnetic anisotropy (PMA). The interlayer exchange coupling (IEC) interaction allows a tilted easy axis of the perpendicular CoTb layer. The main result achieved is the field-free magnetization switching driven by spin-orbit torque (SOT) with a switching direction (clockwise or counterclockwise), which can be controlled by the in-plane direction of the Co magnetization. Meanwhile, we demonstrate that the IEC also induces the asymmetric bubble expansion in the CoTb layer in field-driven experiments and favors the propagation of the domain walls (DWs) with internal magnetization antiparallel to the in-plane IEC field. Our results demonstrate versatile control of the DW motion by noncollinear IEC, which paves a potential way for designing energy-efficient spintronic memory and logic devices, as well as provides a promising and high-efficiency approach for detecting the IEC type by magneto-optical Kerr effect (MOKE) in T-type magnetic heterojunction.