Spin-orbit torque induced magnetization switching in tungsten/ thulium iron garnet bilayer
Magnetization switching by current-induced spin-orbit torque (SOT) is of great interest for its potential application in ultralow-power non-volatile memory devices. The past research on SOT based MRAM heavily relies on the spin-dependent transport in ferromagnetic (FM) conductors. However, such system has additional energy dissipation due to the Joule heating in the metallic FM layer. Moreover, the propagation length of spin current is limited by the short spin-diffusion length and the strong magnetic damping in FM metals. Magnetic insulators (MIs), attract tremendous interest for ultralow-power spintronics and spin wave application recently due to low Gilbert damping and absence of Ohmic loss. In this thesis, we achieved magnetic switching of an insulating magnetic ferrite thulium iron garnet (TmIG) by current-induced SOT in the nonmagnetic metal (NM) tungsten (W) layer. The switching current density is as low as 7.5 ï¿½ 1010 A/m2 for the W (5 nm)/TmIG (15 nm). Further thickness dependent study shows the SOT efficiency increases with the thickness of TmIG, which is in consistence with the theoretical proposed Ms-effect. This finding shed light on the understanding of SOT in MIs and promote the development of MI-based low-power spintronics.