Absence of a giant spin Hall effect in plasma-hydrogenated graphene

TL;DR

This study investigates whether hydrogenation enhances the spin Hall effect in graphene and finds no evidence of a significant SHE despite increased spin-orbit interaction.

Contribution

The paper provides a comparative analysis of two measurement methods showing the absence of a giant spin Hall effect in plasma-hydrogenated graphene.

Findings

Nonlocal resistance observed is not due to spin-related effects.

Hydrogenation does not produce a sizable spin Hall effect in graphene.

Results challenge previous predictions about hydrogenation enhancing SHE.

Abstract

The weak spin-orbit interaction in graphene was predicted to be increased, e.g., by hydrogenation. This should result in a sizable spin Hall effect (SHE). We employ two different methods to examine the spin Hall effect in weakly hydrogenated graphene. For hydrogenation we expose graphene to a hydrogen plasma and use Raman spectroscopy to characterize this method. We then investigate the SHE of hydrogenated graphene in the H-bar method and by direct measurements of the inverse SHE. Although a large nonlocal resistance can be observed in the H-bar structure, comparison with the results of the other method indicate that this nonlocal resistance is caused by a non-spin-related origin.