# Dirac fermions in borophene

## TL;DR

This paper demonstrates that monolayer boron, specifically the eta 12 boron sheet, hosts Dirac fermions similar to graphene, confirmed by experiments and calculations, opening new avenues for high-speed electronic devices.

## Contribution

It reveals that the eta 12 boron sheet can host Dirac cones due to its lattice structure, confirmed by experimental and theoretical methods, establishing borophene as a new Dirac material platform.

## Key findings

- The eta 12 boron sheet hosts Dirac cones similar to graphene.
- Periodic perturbations can split the Dirac cones.
- Experimental and first-principles calculations confirm the electronic structure.

## Abstract

Honeycomb structures of group IV elements can host massless Dirac fermions with non-trivial Berry phases. Their potential for electronic applications has attracted great interest and spurred a broad search for new Dirac materials especially in monolayer structures. We present a detailed investigation of the \beta 12 boron sheet, which is a borophene structure that can form spontaneously on a Ag(111) surface. Our tight-binding analysis revealed that the lattice of the \beta 12-sheet could be decomposed into two triangular sublattices in a way similar to that for a honeycomb lattice, thereby hosting Dirac cones. Furthermore, each Dirac cone could be split by introducing periodic perturbations representing overlayer-substrate interactions. These unusual electronic structures were confirmed by angle-resolved photoemission spectroscopy and validated by first-principles calculations. Our results suggest monolayer boron as a new platform for realizing novel high-speed low-dissipation devices.