Spin-orbit torques in NbSe${}_2$/Permalloy bilayers

Abstract

We present measurements of current-induced spin-orbit torques generated by NbSe${}_2$, a fully-metallic transition-metal dichalcogenide material, made using the spin-torque ferromagnetic resonance (ST-FMR) technique with NbSe${}_2$/Permalloy bilayers. In addition to the out-of-plane Oersted torque expected from current flow in the metallic NbSe${}_2$ layer, we also observe an in-plane antidamping torque with torque conductivity ${\sigma }_S\approx 10^3(\hslash /2e)$($\Omega$m)${}^{-1}$ and indications of a weak field-like contribution to the out-of-plane torque oriented opposite to the Oersted torque. Furthermore, in some samples we also measure an in-plane field-like torque with the form $\hat{m}\times \hat{z}$, where $\hat{m}$ is the Permalloy magnetization direction and $\hat{z}$ is perpendicular to the sample plane. The size of this component varies strongly between samples and is not correlated with the NbSe${}_2$ thickness. A torque of this form is not allowed by the bulk symmetries of NbSe${}_2$, but is consistent with symmetry breaking by a uniaxial strain that might result during device fabrication.

14 pages, 3 figures

References in corpus (4)

• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Thickness dependence of spin-orbit torques generated by WTe2
• Spin-orbit torques from interfacial spin-orbit coupling for various interfaces
• Disentangling relativistic spin torques in a ferromagnet/semiconductor bilayer

Cited by in corpus (1)

• Current-Induced Torques with Dresselhaus Symmetry Due to Resistance Anisotropy in 2D Materials