Picosecond all-electrical perpendicular magnetization switching.

Current-induced spin-orbit torque (SOT) is an effective approach to manipulate magnetic states in spintronic devices. Recent studies show picosecond electrical pulses can induce coherent magnetization switching, reducing switching time from nanosecond scale to picosecond scale. However, it remains unclear whether such ultrafast switching can be achieved in a perpendicular magnetic anisotropy system without an external magnetic field. Here, we demonstrate picosecond all-electrical magnetization switching in a CoTb/Ti/CoFeB/MgO heterostructure, where the in-plane magnetized CoTb layer acts as the SOT source, generating simultaneously in-plane spin current σy and out-of-plane spin current σz. The strong spin-orbit coupling in Tb significantly enhances the SOT efficiency, enabling 16 ps switching with projected 41 fJ/bit consumption in a 100×100 nm² device. Micromagnetic simulations and numerical analysis reveal trade-off between pulse width and energy consumption and identify an optimal σz/σy ratio for energy-efficient switching. Our work promotes the frequency of spintronic devices toward THz regime.