Spin Hall angle versus spin diffusion length: Tailored by impurities

We performed ab initio studies to search for materials where a large spin Hall effect caused by skew scattering is accompanied by a long spin diffusion length. Samples with such properties are promising candidates for all-metallic spintronics devices. Here we consider Cu, Au, and Pt hosts which are typical materials used in experiments. In particular, we identified light impurities such as C and N in Au and heavy impurities such as Bi in Cu to meet this criterion. They exhibit a large spin Hall angle (alpha > 0.06) and an appropriate spin diffusion length of about 100 nm. In addition, a pronounced dependence of the spin diffusion length on the scattering properties of the impurity is found for Cu and Au hosts, in contrast to Pt where much smaller variations are obtained.