Electrostatic forces above graphene nanoribbons and edges interpreted as partly hydrogen-free

TL;DR

This study demonstrates the measurement of electrostatic forces at the edges of partly hydrogen-free graphene nanoribbons using advanced microscopy techniques, revealing insights into their charge distribution and magnetic properties.

Contribution

It introduces a novel bimodal microscopy method with soft cantilevers to detect weak electrostatic forces at graphene nanoribbon edges, especially in hydrogen-free conditions.

Findings

Electrostatic forces are measurable at nanoribbon edges and corners.

Edges are mainly hydrogen-free, enabling magnetic property investigations.

Enhanced sensitivity allows imaging of weak long-range electrostatic forces.

Abstract

Graphene nanoribbons' electronic transport properties strongly depend on the type of edge, armchair, zigzag or other, and on edge functionalization that can be used for band-gap engineering. For only partly hydrogenated edges interesting magnetic properties are predicted. Electric charge accumulates at edges and corners. Scanning force microscopy has so far shown the centre of graphene nanoribbons with atomic resolution using a quartz crystal tuning fork sensor of high stiffness. Weak long-range electrostatic forces related to the charge accumulation on the edges of graphene nanoribbons could not be imaged so far. Here, we show the electrostatic forces at the corners and edges of graphene nanoribbons are amenable to measurement. We use soft cantilevers and a bimodal imaging technique to combine enhanced sensitivity to weak long-range electrostatic forces with the high resolution of the second-frequency shift. Additionally, in our work the edges of the nanoribbons are mainly hydrogen-free, opening to the route to investigations of partly hydrogenated magnetic nanoribbons.