Enhanced spin-orbit coupling in dilute fluorinated graphene

TL;DR

This paper demonstrates a significant enhancement of spin-orbit coupling in dilute fluorinated graphene, enabling room-temperature spin Hall effect detection, which is promising for future spintronics applications.

Contribution

The study provides a systematic analysis of how dilute fluorination enhances SOC in graphene, achieving values much higher than intrinsic SOC.

Findings

SOC values of ~5.1 meV and ~9.1 meV at low fluorination levels

High charge mobility maintained in fluorinated samples

Detection of spin Hall effect at room temperature

Abstract

The preservation and manipulation of a spin state mainly depends on the strength of the spin-orbit interaction. For pristine graphene, the intrinsic spin-orbit coupling (SOC) is only in the order of few ueV, which makes it almost impossible to be used as an active element in future electric field controlled spintronics devices. This stimulates the development of a systematic method for extrinsically enhancing the SOC of graphene. In this letter, we study the strength of SOC in weakly fluorinated graphene devices. We observe high non-local signals even without applying any external magnetic field. The magnitude of the signal increases with increasing fluorine adatom coverage. From the length dependence of the non-local transport measurements, we obtain SOC values of ~ 5.1 meV and ~ 9.1 meV for the devices with ~ 0.005% and ~ 0.06% fluorination, respectively. Such a large enhancement, together with the high charge mobility of fluorinated samples (u~4300 cm2/Vs - 2700 cm2/Vs), enables the detection of the spin Hall effect even at room temperature.