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

TL;DR

This study investigates the intrinsic spin Hall effect in 4d and 5d transition metals using spin absorption in lateral spin valves, revealing a systematic sign change in spin Hall conductivity linked to d-electron count.

Contribution

It provides experimental evidence of the intrinsic spin Hall effect in transition metals and correlates the sign change with d-electron number, aligning with theoretical predictions.

Findings

Spin Hall conductivities measured for Nb, Ta, Mo, Pd, Pt.

Sign of spin Hall conductivity varies systematically with d-electron count.

Results agree with recent theoretical calculations of intrinsic spin Hall effect.

Abstract

We have investigated spin Hall effects in 4$d$ and 5$d$ 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.