Ab initio calculation of intrinsic spin Hall conductivity of Pd and Au

An ab initio relativistic band structure calculation of spin Hall conductivity (SHC) (sigma(z)(xy)) in Pd and Au metals has been performed. It is found that at low temperatures, intrinsic SHCs for Pd and Au are, respectively, similar to 1400 and similar to 400 (h/e) (Omega cm)(-1). The large SHC in Pd comes from the resonant contribution from the spin-orbit splitting of the doubly degenerated 4d bands near the Fermi level at symmetry Gamma and X points, and the smaller SHC in Au is due to the broad free-electron- like 6s6p bands. However, as the temperature increases, the SHC in Pd decreases monotonically and reduces to similar to 330 (h/e) (Omega cm)(-1) at 300 K, while the SHC in Au increases steadily and reaches similar to 750 (h/e) (Omega cm)(-1) at room temperature. This indicates that the gigantic spin Hall effect [sigma(z)(xy) approximate to 10(5) (h/e) (Omega cm)(-1) observed recently in the Au/FePt system [T. Seki et al., Nature Mater. 7, 125 (2008)] is due to the extrinsic mechanisms such as the skew scattering by the impurities in Au. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3054362]