Dirac Point and Edge States in a Microwave Realization of Tight-Binding Graphene-like Structures

TL;DR

This study demonstrates a microwave-based physical model of graphene-like structures that exhibits Dirac points and edge states, providing insights into their properties through reflection measurements.

Contribution

It introduces a novel microwave realization of tight-binding graphene-like lattices using dielectric discs, enabling direct observation of Dirac points and edge states.

Findings

Dirac point observed in microwave reflection measurements

Edge states detected at zigzag edges and corners

Linear dispersion near the Dirac point confirmed

Abstract

We present a microwave realization of finite tight-binding graphene-like structures. The structures are realized using discs with a high index of refraction. The discs are placed on a metallic surface while a second surface is adjusted atop the discs, such that the waves coupling the discs in the air are evanescent, leading to the tight-binding behavior. In reflection measurements the Dirac point and a linear increase close to the Dirac point is observed, if the measurement is performed inside the sample. Resonances due to edge states are found close to the Dirac point if the measurements are performed at the zigzag-edge or at the corner in case of a broken benzene ring.