Spin orbit torques in Pt-based heterostructures with van der Waals interface* *Project supported by the National Natural Science Foundation of China (Grant Nos. 51732010, 51802341, and 12004415), the China Postdoctoral Science Foundation (Grant Nos. 2020M671592, 2019M661965), and the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20200255).

Abstract

Spin orbit torques (SOTs) in ferromagnet/heavy-metal heterostructures have provided great opportunities for efficient manipulation of spintronic devices. However, deterministically field-free switching of perpendicular magnetization with SOTs is forbidden because of the global two-fold rotational symmetry in conventional heavy-metal such as Pt. Here, we engineer the interface of Pt/Ni heterostructures by inserting a monolayer MoTe2 with low crystal symmetry. It is demonstrated that the spin orbit efficiency, as well as the out-of-plane magnetic anisotropy and the Gilbert damping of Ni are enhanced, due to the effect of orbital hybridization and the increased spin scatting at the interface induced by MoTe2. Particularly, an out-of-plane damping-like torque is observed when the current is applied perpendicular to the mirror plane of the MoTe2 crystal, which is attributed to the interfacial inversion symmetry breaking of the system. Our work provides an effective route for engineering the SOT in Pt-based heterostructures, and offers potential opportunities for van der Waals interfaces in spintronic devices.