Modulation of spin conversion in a 1.5 nm-thick Pd film by ionic gating

TL;DR

This study demonstrates that ionic gating can effectively modulate the spin-orbit interaction and spin Hall conductivity in ultrathin Pd films, advancing the understanding of gate-tunable spin phenomena in solid-state systems.

Contribution

It provides experimental evidence of gate-controlled modulation of spin Hall effects in ultrathin Pd films, linking Fermi level shifts to changes in spin-orbit interaction.

Findings

Gate-induced charge accumulation shifts Fermi level in Pd

Gating significantly modulates inverse spin Hall effect signals

Results support gate-tunable spin Hall conductivity in ultrathin films

Abstract

Gate-induced modulation of the spin-orbit interaction (SOI) in a 1.5 nm-thick Pd thin film grown on a ferrimagnetic insulator was investigated. Efficient charge accumulation by ionic gating enables a substantial upshift in the Fermi level of the Pd film, which was corroborated by suppression of the resistivity in the Pd. Electromotive forces arising from the inverse spin Hall effect in Pd under spin pumping were substantially modulated by the gating, in consequence of the modulation of the spin Hall conductivity of Pd as in an ultrathin Pt film. The same experiment using a thin Cu film, for which the band structure is largely different from Pd and Pt and its SOI is quite small, provides further results supporting our claim. The results obtained help in developing a holistic understanding of the gate-tunable SOI in solids and confirm a previous explanation of the significant modulation of the spin Hall conductivity in an ultrathin Pt film by gating.