Evidence for Dirac Fermions in a Honeycomb Lattice Based on Silicon

TLDR

Silicene, a silicon honeycomb lattice, was proposed as a new Dirac‑type electron system analogous to graphene. We used scanning tunneling microscopy and spectroscopy on silicene grown on Ag(111) to investigate its atomic and electronic structure. The measurements revealed a √3×√3 reconstruction explained by an extra‑buckling model, pronounced quasiparticle interference patterns from intervalley and intravalley scattering, and a linear energy‑momentum dispersion with a large Fermi velocity, confirming Dirac fermions in silicene.

Abstract

Silicene, a sheet of silicon atoms in a honeycomb lattice, was proposed to be a new Dirac-type electron system similar to graphene. We performed scanning tunneling microscopy and spectroscopy studies on the atomic and electronic properties of silicene on Ag(111). An unexpected √3 × √3 reconstruction was found, which is explained by an extra-buckling model. Pronounced quasiparticle interferences (QPI) patterns, originating from both the intervalley and intravalley scatter, were observed. From the QPI patterns we derived a linear energy-momentum dispersion and a large Fermi velocity, which prove the existence of Dirac fermions in silicene.