Spin–Orbit Torques in NbSe₂/Permalloy Bilayers

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 σ S ≈ 10 3 (ℏ/2 e )(Ωm) −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 m ̂ × z ̂, where m ̂ is the Permalloy magnetization direction and 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.