Ultrafast field-free magnetization switching using bi-directional spin Hall current and antiferromagnetic interlayer exchange

摘要

We present an approach to realize ultrafast field-free spin-orbit torque (SOT) switching of a ferromagnetic layer with perpendicular magnetic anisotropy. In this scheme, the heavy metal layer serves as both the spin Hall channel and the interlayer exchange spacer. The magnetization switching of the adjacent ferromagnetic layer is driven by magnetic inertia, exhibiting intriguing and rich switching behavior under current pulses of different amplitudes and durations. Based on the macrospin simulation, we investigated the switching behavior of the composite-free layer, i.e., two antiferromagnetically coupled ferromagnetic layers, and demonstrated the possibility of field-free switching within tens of picoseconds. Our results show that the positive sign product of field-like SOT and damping-like SOT and the strong antiferromagnetic exchange between the two coupled ferromagnetic layers are critical to realize the deterministic switching. This work is expected to stimulate further experimental efforts for designing high performance magnetic random-access memory" application. Published under license by AIP Publishing.