Current-Induced magnetization switching by the high spin Hall conductivity $\alpha$-W

Abstract

The spin Hall effect originating from 5d heavy transition metal thin films such as Pt, Ta, and W is able to generate efficient spin-orbit torques that can switch adjacent magnetic layers. This mechanism can serve as an alternative to conventional spin-transfer torque for controlling next-generation magnetic memories. Among all 5d transition metals, W in its resistive amorphous phase typically shows the largest spin-orbit torque efficiency ~ 0.20-0.50. In contrast, its conductive and crystalline $\alpha$ phase possesses a significantly smaller efficiency ~ 0.03 and no spin-orbit torque switching has yet been realized using $\alpha$-W thin films as the spin Hall source. In this work, through a comprehensive study of high quality W/CoFeB/MgO and the reversed MgO/CoFeB/W magnetic heterostructures, we show that although amorphous-W has a greater spin-orbit torque efficiency, the spin Hall conductivity of $\alpha$-W ($|{\sigma }_{\mathrm{SH}}^{\alpha -W}|=3.71\times 10^5{\Omega }^{-1}{m}^{-1}$) is ~3.5 times larger than that of amorphous-W ($|{\sigma }_{\mathrm{SH}}^{amorphous-W}|=1.05\times 10^5{\Omega }^{-1}{m}^{-1}$). Moreover, we demonstrate spin-orbit torque driven magnetization switching using a MgO/CoFeB/$\alpha$-W heterostructure. Our findings suggest that the conductive and high spin Hall conductivity $\alpha$-W can be a potential candidate for future low power consumption spin-orbit torque memory applications.

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Cited by in corpus (6)

• Benchmarking of spin-orbit torque switching efficiency in Pt alloys
• Materials Requirements of High-Speed and Low-Power Spin-Orbit-Torque Magnetic Random-Access Memory
• Efficient Spin-Orbit Torque Generation in Semiconducting WTe2 with Hopping Transport
• Pulse-width and Temperature Dependence of Memristive Spin-Orbit Torque Switching
• Unified Framework for Charge-Spin Interconversion in Spin-Orbit Materials
• Violation of local reciprocity in charge-orbital interconversion