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 HfO₂ gate oxide with resistive switching characteristics is demonstrated. By inducing soft breakdown in the HfO₂ 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 HfO₂ 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.