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 Co/Ta/CoTb/Pt where the bottom Co layer has in-plane magnetic anisotropy and the top CoTb layer has perpendicular magnetic anisotropy. The interlayer exchange coupling interaction allows a tilted easy axis of perpendicular CoTb layer. The main result achieved is the field-free magnetization switching driven by spin-orbit torque (SOT) with a switching direction (clock-wise or counter clock-wise) which can be controlled by the in-plane direction of the Co magnetization. Meanwhile, we demonstrate that the interlayer exchange coupling also induces the asymmetric bubble expansion in the CoTb layer in field-driven experiments and favors the propagation of the domain walls with internal magnetization antiparallel to the in-plane interlayer exchange coupling field. Our results demonstrate versatile control of the domain wall motion by noncolinear interlayer exchange coupling, 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 interlayer exchange coupling type by magneto-optical Kerr effect in T-type magnetic heterojunction.