Manipulation of edge states in microwave artificial graphene

TL;DR

This paper experimentally investigates how uniaxial strain affects edge states in microwave artificial graphene, revealing controllable manipulation of their existence and structure, and discovering a new corner state at edge intersections.

Contribution

It demonstrates experimental control of edge states in artificial graphene using strain and introduces the observation of a novel corner state at edge intersections.

Findings

Uniaxial strain controls edge state existence and spatial extension.

Edge states can be manipulated by a single strain parameter.

A new zero-energy corner state is observed at edge intersections.

Abstract

Edge states are one important ingredient to understand transport properties of graphene nanoribbons. We study experimentally the existence and the internal structure of edge states under uniaxial strain of the three main edges: zigzag, bearded, and armchair. The experiments are performed on artificial microwave graphene flakes, where the wavefunctions are obtained by direct imaging. We show that uniaxial strain can be used to manipulate the edge states: a single parameter controls their existence and their spatial extension into the ribbon. By combining tight-binding approach and topological arguments, we provide an accurate description of our experimental findings. A new type of zero-energy state appearing at the intersection of two edges, namely the corner state, is also observed and discussed.