Magnetization switching through giant spin-orbit torque in the magnetically doped topological insulators

Recent demonstrations of magnetization switching induced by in-plane current in heavy metal/ferromagnetic heterostructures (HMFHs) have drawn great interest to spin torques arising from the large spin-orbit coupling (SOC)...[1-3] in heavy metals. Considering the intrinsic strong SOC, topological insulators (TIs) are expected to be promising candidates for exploring spin-orbit torque (SOT)-related physics...[4, 5]. In this talk, we report the magnetization switching through giant SOT in the magnetically doped TI structures. In particular, we demonstrate the magnetization switching in a chromium-doped TI bilayer heterostructure, and the current induced SOT possibly has contribution from the spin-momentum locked surface states of TI. The critical current density for switching is below 8.9 $\times$ 10$^{4}$A/cm$^{2}$ at 1.9 K. Moreover, we use second-harmonic methods to measure the spin torque efficiencies which are more than three orders of magnitude larger than those reported in heavy metals. The giant SOT and efficient current-induced magnetization switching exhibited by the bilayer heterostructure may lead to innovative spintronics applications such as ultralow power dissipation memory and logic devices.\\[4pt] [1] L. Liu\textit{ et al.}, Science \textbf{336}, 555 (2012).\\[0pt] [2] L. Liu\textit{ et al.}, Phys. Rev. Lett. \textbf{109}, 096602 (2012).\\[0pt] [3] I. M. Miron\textit{ et al.}, Nature \textbf{476}, 189 (2011).\\[0pt] [4] Y. Fan\textit{ et al.}, Nature Mater. \textbf{13}, 699 (2014).\\[0pt] [5] A. R. Mellnik\textit{ et al.}, Nature \textbf{511}, 449 (2014).