Giant Inverse Spin Hall Effect in Bi Doped PtBi Alloy

For generating or detecting spin currents without ferromagnetic materials in spintronic devices, nonmagnetic materials with large spin Hall angles would elicit extreme interest. A giant inverse spin Hall effect (ISHE) generating in Pt doped with 8% Bi by composition is demonstrated. From a combination of ferromagnetic resonance, spin pumping, and ISHE experiments, a large spin current is found induced in an yttrium iron garnet/Pt0.92Bi0.08 bilayer. The spin diffusion length and spin Hall angle of the Pt0.92Bi0.08 alloy are lambda(SD) = 3.3 +/- 0.1 nm and theta(SH) = 0.106 +/- 0.005, respectively. In the experiments, the spin-charge conversion of this alloy is twice that of Pt and is larger than most reported heavy metals. Such enhancement can be attributed to the skew scattering from the high atomic number of Bi impurities via the spin-orbit interaction.