Ab Initio Investigations of a Two Dimensional form of Silicon featuring Dispersionless Electronic States

Materials with dispersionless electronic states (or flat bands) have been intensely investigated in recent years, owing to their association with strongly correlated electrons. Due to the negligible kinetic energies of electrons in such states, the electron-electron interaction dominates, thus resulting in superconductivity, ferromagnetism, and other exotic phases of matter. While a number of bulk materials and heterostructures have been investigated for their connection with flat-band physics, the discovery of new, simple low-dimensional materials with such electronic features, continues to be an alluring possibility. Following this line of thought, and motivated by the consideration that silicon is a versatile material with many known low-dimensional allotropes that have already been experimentally synthesized, we investigate here a two-dimensional form of silicon in the decorated honeycomb (or star) lattice. The proposed material has a buckled structure similar to silicene, consists of dodecagonal rings, and features electronic flat bands near the Fermi-level. We describe extensive first principles investigations into the static and dynamic structural stability of the material and observe that in-plane strains stabilize it. Furthermore, the bandwidth of the flat band is found to be highly tunable with strains. Finally, we investigate the possibility of using substrates to apply such stabilizing strains, suggesting the fabricability of this novel two dimensional material under experimental conditions.