Lithium‐Ion Battery Technology for Voltage Control of Perpendicular Magnetization

Abstract The voltage control of magnetism is a promising path to the development of low‐power spintronic devices. Magneto‐ionics—exploiting voltage‐driven ion migration to control magnetism—has attracted interest because it can generate large magnetoelectric effects at low voltage. Here, the use of the solid‐state lithium‐ion battery technology for reversible voltage‐controlled switching between perpendicular and in‐plane magnetization states in a Co–Pt bilayer is demonstrated. Due to the small size and high mobility of lithium ions, small voltages produce an exceptionally high magnetoelectric coupling efficiency of at least 7700 fJ V^–1 m^–1 at room temperature. The magnetic switching effect is attributed to the modulation of spin‐orbit coupling at the Co–Pt interface when lithium ions migrate between a lithium storage layer (LiCoO₂) and the magnetic interface across a lithium phosphorous oxynitride (LiPON) solid‐state electrolyte, which is corroborated by density functional theory calculations. Voltage control of magnetism in the battery structure does not show degradation over more than 500 voltage cycles, demonstrating promise for solid‐state lithium‐based magneto‐ionic devices.