[Prof. Gil-Ho Lee] Spin-orbit Torque Switching in an All-Van der Waal…

caption: The schematic of a next-generation memory device based on spin-orbit torque. A spin current (red arrow) generated from a charge current (yellow arrow) in a topological material (WTe2) is injected into a magnetic material (Fe3GeTe2).  

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

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 (ξ) and electrical conductivity (σ), and an efficient spin injection across a transparent interface. Herein, we use single crystals of the van der Waals (vdW) topological semimetal WTe2 and vdW ferromagnet Fe3GeTe2 to satisfy the requirements in their all-vdW-heterostructure with an atomically sharp interface. The results exhibit values of ξ ≈ 4.6 and σ ≈ 2.25 × 105 Ω–1m–1 for WTe2. Moreover, we obtain the significantly reduced switching current density of 3.90 × 106 A/cm2 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.