Enhanced Inverse Spin-Hall Effect in Ultrathin Ferromagnetic/Normal Metal Bilayers

TL;DR

This study demonstrates enhanced inverse spin-Hall effect in ultrathin Co/Pt bilayers, revealing increased spin-to-charge conversion efficiency as cobalt thickness decreases below 2 nm, supported by experimental measurements and theoretical modeling.

Contribution

It provides new insights into spin pumping in ultrathin ferromagnetic/normal metal bilayers and introduces a theory linking impurity scattering to surface roughness effects.

Findings

Spin pumping voltage increases as cobalt thickness decreases below 2 nm.

Enhanced spin-to-charge conversion efficiency observed in ultrathin bilayers.

Angular dependence distinguishes spin pumping from rectification voltages.

Abstract

We measure electrically detected ferromagnetic resonance in microdevices patterned from ultra-thin Co/Pt bilayers. Spin pumping and rectification voltages are observed and distinguished via their angular dependence. The spin-pumping voltage shows an unexpected increase as the cobalt thickness is reduced below 2 nm. This enhancement allows more efficient conversion of spin to charge current and motivates a theory modelling the dependence of impurity scattering on surface roughness.