Spin–orbit torque-assisted switching in magnetic insulator thin films with perpendicular magnetic anisotropy

As an in-plane charge current flows in a heavy metal film with spin–orbit coupling, it produces a torque on and thereby switches the magnetization in a neighbouring ferromagnetic metal film. Such spin–orbit torque (SOT)-induced switching has been studied extensively in recent years and has shown higher efficiency than switching using conventional spin-transfer torque. Here we report the SOT-assisted switching in heavy metal/magnetic insulator systems. The experiments used a Pt/BaFe(12)O(19) bilayer where the BaFe(12)O(19) layer exhibits perpendicular magnetic anisotropy. As a charge current is passed through the Pt film, it produces a SOT that can control the up and down states of the remnant magnetization in the BaFe(12)O(19) film when the film is magnetized by an in-plane magnetic field. It can reduce or increase the switching field of the BaFe(12)O(19) film by as much as about 500 Oe when the film is switched with an out-of-plane field.