Field-free control and switching of perpendicular magnetization by voltage induced manipulation of RKKY interaction

Voltage control of magnetization offers substantial advantages in energy efficiency for the development of spintronics technology. However, achieving a complete 180^̊ magnetization switching remains as a challenging task since the electric field cannot provide torques to turn the magnetic moment in the ferromagnetic material. To address this challenge, we explore the utilization of synthetic antiferromagnetic (sAFM) structure coupled by Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in the two ferromagnetic (FM) Co layers separated by a suitable thickness Ru spacer layer. One of the FM layers was prepared to be in contact with the GdO_x layer, where ionic motion of oxygen can be manipulated via an application of electric field. Depending on the oxidation state at the interface with GdO_x, the RKKY coupling can be adjusted and achieves reversible transitions between antiferromagnetic (AFM) and FM orders of FM layers at room temperature. The transition is mediated by the migration and redistribution of oxygen ions, transforming the Co/Gd interface into Co/GdO_x and vice versa. This method suggests a stable and electrical route for magnetization reversals without an external magnetic field.