Current-Induced In-Plane Magnetization Switching in a Biaxial Ferrimagnetic Insulator

Ferrimagnetic insulators (FiMI) have been intensively used in microwave and magneto-optical devices as well as spin caloritronics, where their magnetization direction plays a fundamental role on the device performance. The magnetization is generally switched by applying external magnetic fields. Here we investigate current-induced spin-orbit-torque switching of the magnetization in ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ ($\mathrm{YIG}$)/$\mathrm{Pt}$ bilayers with in-plane magnetic anisotropy, where the switching is detected by spin Hall magnetoresistance. Reversible switching is found at room temperature for a threshold current density of ${10}^{7}\phantom{\rule{0.1em}{0ex}}\mathrm{A}\phantom{\rule{0.1em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2}$. The $\mathrm{YIG}$ sublattices with antiparallel and unequal magnetic moments are aligned parallel or antiparallel to the direction of current pulses, which is consistent to the N\'eel-order switching in an antiferromagnetic system. It is proposed that such a switching behavior may be triggered by the antidamping torque acting on the two antiparallel sublattices of FiMI. Our finding not only broadens the magnetization switching by electrical means and promotes the understanding of magnetization switching, but also paves the way for all-electrically modulated microwave devices and spin caloritronics with low power consumption.