Spin-orbit torque in chemically disordered and L11-ordered Cu100−xPtx

The binary alloys with heavy elements have been considered promising candidates for spin-orbit torque application due to the tunable spin Hall effect. In light of previous studies, the effect of crystalline structure on spin Hall effect in nonmagnetic alloys has not been thoroughly studied. Here, we present a systematic investigation of the spin-orbit torques in chemically disordered $\mathrm{C}{\mathrm{u}}_{100\text{\ensuremath{-}}x}\mathrm{P}{\mathrm{t}}_{x}$ and $\mathrm{L}{1}_{1}\text{\ensuremath{-}}\mathrm{C}{\mathrm{u}}_{50}\mathrm{P}{\mathrm{t}}_{50}$ by the spin torque ferromagnetic resonance technique. The results indicate that both the atomic concentration and the degree of the chemical ordering substantially influence the spin-orbit torque efficiency of the CuPt alloys. In chemically disordered $\mathrm{C}{\mathrm{u}}_{100\text{\ensuremath{-}}x}\mathrm{P}{\mathrm{t}}_{x}$, the primary mechanism of spin Hall effect changes from extrinsic to intrinsic when the Pt concentration is increased to larger than $80%$. In $\mathrm{L}{1}_{1}\text{\ensuremath{-}}\mathrm{C}{\mathrm{u}}_{50}\mathrm{P}{\mathrm{t}}_{50}$ with weak chemical ordering, the side-jump and intrinsic mechanisms dominate, whereas the skew scattering mechanism dominates for strong chemical ordering. This work provides a perspective to control the spin-orbit torques in alloys.