Experimental observation of Dirac cones in artificial graphene lattices

TL;DR

This paper reports the creation of macroscopic artificial graphene lattices through self-assembly of C60 molecules, with experimental and theoretical evidence confirming Dirac cones, advancing the development of quantum devices.

Contribution

It demonstrates a scalable method to synthesize artificial graphene with confirmed Dirac cones, enabling practical device applications and detailed electronic structure studies.

Findings

Confirmation of Dirac cones at K points via ARPES

Successful self-assembly of C60 molecules into honeycomb lattices

Potential for exploring exotic properties in artificial lattices

Abstract

Artificial lattices provide a tunable platform to realize exotic quantum devices. A well-known example is artificial graphene (AG), in which electrons are confined in honeycomb lattices and behave as massless Dirac fermions. Recently, AG systems have been constructed by manipulating molecules using scanning tunnelling microscope tips, but the nanoscale size typical for these constructed systems are impossible for practical device applications and insufficient for direct investigation of the electronic structures using angle-resolved photoemission spectroscopy (ARPES). Here, we demonstrate the synthesis of macroscopic AG by self-assembly of C$_{60}$ molecules on metal surfaces. Our theoretical calculations and ARPES measurements directly confirm the existence of Dirac cones at the $K$ ($K^\prime$) points of the Brillouin zone (BZ), in analogy to natural graphene. These results will stimulate ongoing efforts to explore the exotic properties in artificial lattices and provide an important step forward in the realization of novel molecular quantum devices.