Tailoring of the extrinsic spin Hall effect in disordered metal alloys

We present a first-principles study of the extrinsic spin Hall effect in dilute metallic alloys and show how tailoring the magnitude of the spin Hall conductivity can be achieved by materials design concerning composition and varying the concentration of the alloy partners. An essential ingredient is the relative strength of the spin-orbit coupling of host and impurity partner. This is systematically studied by changing alloy composition and performing model calculations in which the spin-orbit coupling strength is scaled. The calculations reveal that changing the impurity concentration affects the extrinsic contributions, namely skew scattering and side jump, differently. This is put into the context of recent model calculations put forward by Fert and Levy [Phys. Rev. Lett. 106, 157208 (2011), 10.1103/PhysRevLett.106.157208]. A fully relativistic Kubo-Středa formalism as implemented in the multiple-scattering KKR electronic structure method is used. The calculations were carried out for Pd, Pt, and Cu hosts doped with 4 d including Ag and Cd and 5 d impurities including Au and Hg.