Spatially resolved edge currents and guided-wave electronic states in graphene

TL;DR

This paper demonstrates experimentally guided-wave electronic states along graphene edges, revealing charge flow confined to boundaries, which could enable nanoscale information processing similar to optical fiber light guidance.

Contribution

First experimental observation of guided-wave edge states in graphene using superconducting interferometry and Fourier analysis.

Findings

Charge flow guided along crystal boundaries near charge neutrality.

Edge currents interpreted as guided-wave states confined by band bending.

Potential for nanoscale information transduction and processing.

Abstract

A far-reaching goal of graphene research is exploiting the unique properties of carriers to realize extreme nonclassical electronic transport. Of particular interest is harnessing wavelike carriers to guide and direct them on submicron scales, similar to light in optical fibers. Such modes, while long anticipated, have never been demonstrated experimentally. In order to explore this behavior, we employ superconducting interferometry in a graphene Josephson junction to reconstruct the real-space supercurrent density using Fourier methods. Our measurements reveal charge flow guided along crystal boundaries close to charge neutrality. We interpret the observed edge currents in terms of guided-wave states, confined to the edge by band bending and transmitted as plane waves. As a direct analog of refraction-based confinement of light in optical fibers, such nonclassical states afford new means for information transduction and processing at the nanoscale.