Spin-orbit Torque Switching in an All-Van der Waals Heterostructure

Abstract

Current-induced control of magnetization in ferromagnets using spin-orbit torque (SOT) has drawn attention as a new mechanism for fast and energy efficient magnetic memory devices. Energy-efficient spintronic devices require a spin-current source with a large SOT efficiency ($\xi$) and electrical conductivity ($\sigma$), and an efficient spin injection across a transparent interface. Herein, we use single crystals of the van der Waals (vdW) topological semimetal WTe${}_2$ and vdW ferromagnet Fe${}_3$GeTe${}_2$ to satisfy the requirements in their all-vdW-heterostructure with an atomically sharp interface. The results exhibit values of $\xi \approx 4.6$ and $\sigma \approx 2.25\times 10^5{\Omega }^{-1}{m}^{-1}$ for WTe${}_2$. Moreover, we obtain the significantly reduced switching current density of $3.90\times 10^{6}A/c{m}^2$ at 150 K, which is an order of magnitude smaller than those of conventional heavy-metal/ ferromagnet thin films. These findings highlight that engineering vdW-type topological materials and magnets offers a promising route to energy-efficient magnetization control in SOT-based spintronics.

19 pages, 4 figures

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