Tuning Effective Spin Hall Angles via Oxygen Vacancies in Multiferroic BiFeO3‐Based Heterostructures

Recently, magnetization switching driven by spin-orbit torque (SOT) has been intensely studied. However, it is still a challenge to effectively control the spin Hall angle (SHA) and critical current density for SOT switching. With the help of multiferroic BiFeO3 (BFO) thin films, a method to adjust SHA and the switching current is proposed. The BFO-based heterostructures with opposite spontaneous polarization fields show huge changes in both perpendicular magnetic anisotropy and SOT-induced magnetization switching. The variation of the effective SHAs for the heterostructures with opposite polarizations is estimated to be 272%, which can be attributed to the distribution of oxygen vacancies inside the BFO films. The possible applications of these structures in memory and reconfigurable logic devices are also demonstrated.