Indication of intrinsic spin Hall effect in 4d and 5d transition metals

We have investigated spin Hall effects in 4d and 5d transition metals, Nb, Ta, Mo, Pd, and Pt, by incorporating the spin absorption method in the lateral spin valve structure, where large spin current preferably relaxes into the transition metals, exhibiting strong spin-orbit interactions. Thereby nonlocal spin valve measurements enable us to evaluate their spin Hall conductivities. The sign of the spin Hall conductivity changes systematically depending on the number of d electrons. This tendency is in good agreement with the recent theoretical calculation based on the intrinsic spin Hall effect.