Fundamental Properties of Metal-Adsorbed Silicene: A DFT Study
Abstract
Sodium, magnesium and aluminum adatoms, which, respectively, possess one, two and three valence electrons in terms of 3s, 3s2, and (3s2, 3p) orbitals, are very suitable for helping us understand the adsorption-induced diverse phenomena. In this study, the revealing properties of metal (Na/Mg/Al)-adsorbed graphene systems are investigated by mean of the first-principles method. The single- and double-side chemisorption cases, the various adatom concentrations, the hollow/top/valley/bridge sites, and the buckled structures are taken into account. The hollow and valley adsorptions, which, respectively, correspond to the Na/Mg and Al cases, create the extremely non-uniform environments within the Moire superlattices. This lead to diverse orbital hybridizations in Na/Mg/Al-Si bonds, as indicated from the Na/Mg/Al-dominated bands, the spatial charge density distributions and the orbital-projected density of states (DOS). Among three kinds of metal-adatom adsorptions, the Al-adsorption configurations present the strongest chemical modifications. The ferromagnetic configurations are shown to only survive in the specific Mg- and Al-adsorptions, but not the Na-cases. The theoretical predictions could be validated by experimental measurements and the up-to-date potential applications are included. Furthermore, the important similarities and differences with the graphene-related systems are also discussed.