Interband $\pi$-like plasmon in silicene grown on silver

TL;DR

This study demonstrates that a specific plasmon mode in silicene grown on silver persists despite substrate interactions, indicating potential for silicon-based 2D material applications.

Contribution

It provides experimental and theoretical evidence of a c0e-like plasmon in multiphase silicene on Ag(111), showing preserved semimetallic behavior.

Findings

The c0e-like plasmon survives substrate interaction.

Multiphase silicene maintains semimetallic electronic features.

Potential for silicon-based 2D applications is suggested.

Abstract

Silicene, the two-dimensional allotrope of silicon, is predicted to exist in a low-buckled honeycomb lattice, characterized by semimetallic electronic bands with graphenelike energy-momentum dispersions around the Fermi level (represented by touching Dirac cones). Single layers of silicene are mostly synthesized by depositing silicon on top of silver, where, however, the different phases observed to date are so strongly hybridized with the substrate that not only the Dirac cones, but also the whole valence and conduction states of ideal silicene appear to be lost. Here, we provide evidence that at least part of this semimetallic behavior is preserved by the coexistence of more silicene phases, epitaxially grown on Ag(111). In particular, we combine electron energy loss spectroscopy and time-dependent density functional theory to characterize the low-energy plasmon of a multiphase-silicene/Ag(111) sample, prepared at controlled silicon coverage and growth temperature. We find that this mode survives the interaction with the substrate, being perfectly matched with the {\pi}-like plasmon of ideal silicene. We therefore suggest that the weakened interaction of multiphase silicene with the substrate may provide a unique platform with the potential to develop different applications based on two-dimensional silicon systems.