Nanosecond Magneto‐Ionic Control of Magnetism Using a Resistive Switching HfO₂ Gate Oxide

Voltage‐controlled magnetism (VCM) offers an efficient operating method for various spintronic applications, with reduced power consumption compared to conventional current‐driven technologies. Among the VCM mechanisms, magneto‐ionic control provides large modulation and non‐volatile characteristics. However, its operating speed is limited to a microsecond timescale due to slow ion migration, which must be improved for practical device applications. Here, the nanosecond operation of magneto‐ionic VCM in a Ta/CoFeB/MgO/AlO x structure by introducing an HfO 2 gate oxide with resistive switching characteristics is demonstrated. By inducing soft breakdown in the HfO 2 gate oxide, the coercivity of the perpendicularly magnetized CoFeB can be controlled by 20% with a 20 ns gate voltage of ≈7 MV cm −1 . This nanosecond magneto‐ionic VCM performance is maintained after repeated operations up to 10 000 cycles. Further, by utilizing an HfO 2 gate in a spin‐orbit torque (SOT) device, the ability to control field‐free SOT switching polarity with nanosecond gate voltages is demonstrated. These findings provide a novel pathway to realize nanosecond, non‐volatile VCM for low‐power spintronic applications.