Microscopic origin of the π states in epitaxial silicene

We investigated the electronic properties of epitaxial silicene on ZrB_2(0001) thin film grown on Si(111) by means of low-temperature scanning tunneling spectroscopy and density functional theory calculations. The position of silicon atoms and thus, the localization of the valence and conduction states were deducted from the comparison of the spectra and the computed local density of states. We point out the strong contribution of p_z orbitals of specific atoms to those states which indicates the π character of the conduction and valence bands. A clear correlation between hybridization of the orbitals of the Si atoms and the buckling was evidenced