Unconventional in-plane field-like spin–orbit torques induced by rare-earth Dy interface in Py/Dy/Pt tri-layers

Spin transport across an interface in energy-efficient spintronic devices, especially for spin–orbit torque applications, has sparked interest in the spintronics community. Here, we employ a rare-earth metal spacer Dy to modify the interface of a Py-based heterostructure, with the aim of modulating the spin dynamics of the system and thereby controlling the spin–orbit torques. As the thickness of Dy increases, it is found that the saturation magnetization of Py/Dy decreases and eventually reaches a plateau, suggesting the induced magnetic moment of Dy that aligns opposite to the Fe and Ni moments. Such a self-assembled antiferromagnetic interface can be destroyed by the insertion of a Cu layer between Py and Dy. Utilizing this interface effect, an additional spin dissipation is observed by enhancement of spin dynamic damping, which has achieved a high spin mixing conductance at the interface of Py/Dy according to spin pumping theory. Utilizing the Py/Dy interface, an unconventional in-plane field-like torque spin–orbit torque (SOT) in a Py/Dy/Pt structure is achieved, while the field-like SOT efficiency experiences a notable enhancement in the Py/Dy/Pt system. By optimizing the interface between the Dy layer and Pt, it is possible to further enhance the performance and efficiency of the devices, thereby promoting the development of spintronic devices. This discovery has significant implications for the future design of low-power spintronic devices.