The Stability and Charge Carriers in Bilayer Silicene

The structure optimization, phonon, and ab initio finite temperature molecular dynamics calculations have been performed to predict that bilayer silicene has stable structure with AB stacking geometry and is more favorable energetically to synthesize than monolayer silicene, a two-dimensional honeycomb lattice with buckled geometry. Marvellously, its electronic bands show that the charge carriers behave like relativistic Dirac fermions with linear energy dispersions near the K points. An insightful analysis has been presented to understand the low-energy electronic excitations based on tight-binding approximation, and we suggest that the component of sp3 hybridization in the buckled geometry blocks the interlayer hopping, so the linear dispersion can be preserved.