Feature-Rich Quasiparticle Properties of Halogen-Adsorbed Silicene Nanoribbons

Abstract

Structural, electronic, and magnetic properties of halogen (F, Cl, Br, I, and At)-adsorbed armchair and zigzag silicene nanoribbons (ASiNRs and ZSiNRs) are investigated using the density functional theory (DFT) method, in which the halogen-diversified quasiparticle properties can be fully identified through developed first-principles physical quantities including formation energy, atom-dominated band structure, atom- and orbital-projected density of states (DOSs), charge density distribution, magnetic moment, and spin density distribution. Halogen adatoms are optimally adsorbed at the top site of SiNRs among the valley, bridge, and hollow sites, regardless of their concentrations and distributions. For single adatom adsorptions, the direct-gap semiconducting behaviors of ASiNRs become the p-type metallic behaviors, while the direct-gap semiconducting behaviors of ZSiNRs become the p-type metallic behaviors. The metallic-semiconducting transitions of the halogen-adsorbed ASiNRs and ZSiNRs happen at the critical increased concentrations of 50% and 33.33%, respectively. The anti-ferromagnetic configuration of pristine ZSiNRs transforms into the ferromagnetic one in the single adatom-adsorbed systems. Especially, under the double adatom adsorptions, whether the anti-ferromagnetic configuration becomes ferromagnetic or nonmagnetic ones strongly depends on the adatom distributions across the zigzag edges. The ferromagnetic-nonmagnetic transition of the halogen-adsorbed ZSiNRs is found at the critical concentration of 25%. The diverse quasiparticle properties of halogen-adsorbed silicene nanoribbons are very potential for a wide range of applications in electronic and spintronic devices.