Current-induced magnetization switching through spin-orbit torques (SOTs) isthe fundamental building block of spin-orbitronics. The SOTs generally arisefrom the spin-orbit coupling of heavy metals. However, even in aheterostructure where a metallic magnet is sandwiched by two differentinsulators, a nonzero current-induced SOT is expected because of the brokeninversion symmetry; an electrical insulator can be a spin-torque generator.Here, we demonstrate current-induced magnetization switching using aninsulator. We show that oxygen incorporation into the most widely usedspintronic material, Pt, turns the heavy metal into an electrically-insulatinggenerator of the SOTs, enabling the electrical switching of perpendicularmagnetization in a ferrimagnet sandwiched by electrically-insulating oxides. Wefurther found that the SOTs generated from the Pt oxide can be controlledelectrically through voltage-driven oxygen migration. These findings open aroute towards energy-efficient, voltage-programmable spin-orbit devices basedon solid-state switching of heavy metal oxidation.
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