Electrically tunable resonant scattering in fluorinated bilayer graphene

TL;DR

This study demonstrates that fluorine adatoms on bilayer graphene create resonant impurity states that can be electrically tuned, significantly affecting charge carrier scattering and conduction, with implications for spintronic device applications.

Contribution

We experimentally and theoretically show that electric fields can tune resonant scattering from fluorine adatoms in bilayer graphene, revealing a new control mechanism for impurity states.

Findings

Fluorine adatoms induce resonant impurity states near charge neutrality.

Electric field tuning alters the scattering amplitude by nearly twofold.

Resonant scattering impacts conduction and could be harnessed in spintronics.

Abstract

Adatom-decorated graphene offers a promising new path towards spintronics in the ultrathin limit. We combine experiment and theory to investigate the electronic properties of dilutely fluorinated bilayer graphene, where the fluorine adatoms covalently bond to the top graphene layer. We show that fluorine adatoms give rise to resonant impurity states near the charge neutrality point of the bilayer, leading to strong scattering of charge carriers and hopping conduction inside a field-induced band gap. Remarkably, the application of an electric field across the layers is shown to tune the resonant scattering amplitude from fluorine adatoms by nearly twofold. The experimental observations are well explained by a theoretical analysis combining Boltzmann transport equations and fully quantum-mechanical methods. This paradigm can be generalized to many bilayer graphene-adatom materials, and we envision that the realization of electrically tunable resonance may be a key advantage in graphene-based spintronic devices.