Voltage-Controlled Field-Free Switching of RKKY Coupled Multilayers

To reduce the power consumption of spintronic devices, voltage-control of magnetic order is being investigated as an alternative to current-controlled mechanisms. However, switching the magnetization of a metallic magnetic layer 180^○ with only an electric field is impractical because they do not break time-reversal symmetry and decay rapidly in metals. Magneto-ionic (MI) gating has emerged as a solution in which electric fields are used to inject molecules to modify a material’s magnetic properties. We show that MI gating of hydrogen (H) enables dynamic control of the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in a solid-state magnetic multilayer device. We demonstrate that the RKKY coupling can be switched from antiferromagnetic to ferromagnetic, and vice versa, using only a small positive bias. The switching is sub 1 ms at room temperature, fully reversible, and cyclable. H loading enables both an amplitude and phase shift of the oscillatory RKKY coupling. Using an engineered soft layer and hard layer, MI gating of the RKKY interaction allows for 180^○ field-free switching of the soft layer without the need for a biasing layer. This creates new opportunities for memory-based spintronic devices since the free layer can be directly switched with just a small applied voltage.