Spin Hall angle in single-layer graphene

TL;DR

This paper studies the spin Hall effect in single-layer graphene, revealing mesoscopic fluctuations and a universal relation between spin Hall angle deviation and conductivity, supported by experiments and simulations.

Contribution

It uncovers a universal relationship between spin Hall angle fluctuations and conductivity in graphene, supported by theoretical, numerical, and experimental comparisons.

Findings

Spin Hall angle exhibits mesoscopic fluctuations similar to metals.

A universal relation: spin Hall angle deviation times conductivity equals 0.18.

Comparison with experiments and tight-binding simulations confirms the universal behavior.

Abstract

We investigate the spin Hall effect in a single-layer graphene device with disorder and interface-induced spin-orbit coupling. Our graphene device is connected to four semi-infinite leads that are embedded in a {Landauer-B\"uttiker} setup for quantum transport. We show that the spin Hall angle of graphene devices exhibits mesoscopic fluctuations that are similar to metal devices. Furthermore, the product between the {maximum spin Hall angle deviation} and dimensionless longitudinal conductivity follows a universal relationship $\Theta_{sH} \times \sigma = 0.18$. Finally, we compare the universal relation with recent experimental data and numerically exact real-space simulations from the tight-binding model.