The discovery of chiral spin texture has unveiled many
unusual
yet extraordinary physical phenomena, such as the Néel type
domain walls and magnetic skyrmions. A recent theoretical study suggests
that a chiral exchange interaction is not limited to a single ferromagnetic
layer; instead, three-dimensional spin textures can arise from an
interlayer Dzyaloshinskii–Moriya interaction. However, the
influence of chiral interlayer exchange coupling on the electrical
manipulation of magnetization has rarely been addressed. Here, the
coexistence of both symmetric and chiral interlayer exchange coupling
between two orthogonally magnetized CoFeB layers in PtMn/CoFeB/W/CoFeB/MgO
is demonstrated. Images from polar magneto-optical Kerr effect microscopy
indicate that the two types of coupling act concurrently to induce
asymmetric domain wall propagation, where the velocities of domain
walls with opposite chiralities are substantially different. Based
on this microscopic mechanism, field-free switching of the perpendicularly
magnetized CoFeB is achieved with a wide range of W thicknesses of
0.6–4.5 nm. This work enriches the understanding of interlayer
exchange coupling for spintronic applications.