Persistent Dirac Fermion State on Bulk-like Si(111) Surface

TL;DR

This study demonstrates that bulk-like Si(111) surfaces can host Dirac fermions, revealing a new platform for electronic applications beyond monolayer silicene, with observed linear dispersion and surface states.

Contribution

It shows that bulk silicon with diamond structure can host Dirac fermions, expanding the potential materials for Dirac physics beyond two-dimensional silicene.

Findings

Observation of Dirac fermions on bulk Si(111) surface.

Presence of linear energy-momentum dispersion.

Detection of delocalized surface states.

Abstract

The "multilayer silicene" films were grown on Ag(111), with increasing thickness above 30 monolayers (ML). We found that the "multilayer silicene" is indeed a bulk Si(111) film. Such Si film on Ag(111) always exhibits a root(3)xroot(3) honeycomb superstructure on surface. Delocalized surface state as well as linear energy-momentum dispersion was revealed by quasiparticle interference patterns (QPI) on the surface, which proves the existence of Dirac fermions state. Our results indicate that bulk silicon with diamond structure can also host Dirac fermions, which makes the system even more attractive for further applications compared with monolayer silicene.