5d transition metal Pt is the canonical spin Hall material for efficient generation of spin-orbit torques (SOTs) in Pt/ferromagnetic layer (FM) heterostructures. However, for a long while with tremendous engineering endeavors, the damping-like SOT efficiencies (${xi}_{DL}$) of Pt and Pt alloys are still limited to ${xi}_{DL}$<0.5. Here we present that with proper alloying elements, particularly 3d transition metals V and Cr, the strength of the high spin Hall conductivity of Pt (${sigma}_{SH}{sim}6.45{times}10^{5}({hbar}/2e){Omega}^{-1}{cdot} m^{-1}$) can be developed. Especially for the Cr-doped case, an extremely high ${xi}_{DL}{sim}0.9$ in a Pt$_{0.69}$Cr$_{0.31}$/Co device can be achieved with a moderate Pt$_{0.69}$Cr$_{0.31}$ resistivity of ${rho}_{xx}{sim}133 {mu}{Omega}{cdot}cm$. A low critical SOT-driven switching current density of $J_{c}{sim}3.16{times}10^{6} A{cdot}cm^{-2}$ is also demonstrated. The damping constant (${alpha}$) of Pt$_{0.69}$Cr$_{0.31}$/FM structure is also found to be reduced to 0.052 from the pure Pt/FM case of 0.078. The overall high ${sigma}_{SH}$, giant ${xi}_{DL}$, moderate ${rho}_{xx}$, and reduced ${alpha}$ of such Pt-Cr/FM heterostructure makes it promising for versatile extremely low power consumption SOT memory applications.
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