Does the Dirac cone exist in silicene on metal substrates?

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• Silicene, a silicon allotrope, exhibits a Dirac cone crucial for its electronic properties.
• Epitaxial growth of silicene on metal substrates is challenging due to substrate interactions.
• Strong band hybridization often destroys the Dirac cone in silicene on metals.

Purpose of the Study:

• Investigate the commonality of Dirac cone absence in epitaxial silicene on various metal substrates.
• Explore methods to restore the Dirac cone in silicene on metal substrates.
• Provide a pathway for studying silicene's unique properties on conductive substrates.

Main Methods:

• First-principles calculations were employed.
• Simulations covered silicene grown on Iridium (Ir), Copper (Cu), Magnesium (Mg), Gold (Au), Platinum (Pt), Aluminum (Al), and Silver (Ag) substrates.
• The effect of intercalating alkali metal atoms was investigated.

Main Results:

• Absence of the Dirac cone is a common feature for epitaxial silicene on the studied metal substrates due to strong band hybridization.
• Intercalating alkali metal atoms effectively restores the Dirac cone.
• The restored Dirac cone exhibits either linear or parabolic dispersion.

Conclusions:

• Strong band hybridization universally disrupts the Dirac cone in epitaxial silicene on common metal substrates.
• Alkali metal intercalation presents a viable strategy to recover the Dirac cone.
• This method facilitates the investigation of silicene's intrinsic electronic properties on metallic platforms.