Significant Spin‐Capacitive Modulation of Magnetism Through Na ⁺ Motion in Layered FeSe

Abstract Recently, a novel spin‐capacitive method has emerged and distinguishes itself in voltage control of magnetism (VCM) through dual‐phase ion‐electron conduction, exhibiting significant, rapid, and reversible magnetic modulation in several lithium‐ion‐based devices, with promising potential for low‐power applications. Considering the inherent link to neuronal processing, enhanced safety, and superior compatibility with semiconductor integration of sodium‐based devices, the first report on magnetization modulation via Na‐assisted spin capacitance mechanism is presented, showcasing unique advantages over lithium‐based devices. Employing layered FeSe as the regulated material, operando magnetometry demonstrates giant and reversible magnetic modulation, involving On‐Off ferromagnetic switching at high voltages and quasi‐linear magnetization change at low voltages. Comprehensive analyses confirm the spin capacitance characteristics of VCM in low‐voltage regions, achieving a significant modulation amplitude of 12.70 emu g −1 within 1 V. This is facilitated by nearly 100% formation of Fe nanoparticles via the two‐step reaction during Na introduction to layered FeSe. Furthermore, spin‐capacitive magnetic regulation in the devices exhibits superior manipulative characteristics within the low voltage range of 0–0.75 V, notably robust endurance, rapid response, and non‐volatility. This work inspires new avenues for developing low‐power devices featuring high speed, reversibility, non‐volatility, and cost‐effectiveness, especially exhibiting notable advantages in brain‐like simulation applications.