Interactions of Fe atom with single wall armchair SiC nanotubes: an ab initio study

Abstract

A systematic study of Fe atom encapsulation and adsorption in armchair SiC nanotubes (SiCNT) with diameters in the range of 5.313 to 10.582 A has been performed using hybrid density functional theory and a finite cluster approximation. A detailed comparison of the binding energies, equilibrium positions, Mulliken charges, and spin magnetic moments of Fe atoms has been performed for three types of nanotubes. The electronic states, HOMO–LUMO gaps, and changes in gaps with respect to the bare nanotube gaps have been investigated as well. Our results show that the properties of SiCNT can be modified by Fe atom encapsulation and adsorption. Binding energies of the encapsulated and adsorbed systems indicate that these structures are stable and show site dependence. For both cases a significant band gap decrease is observed for type 1 nanotubes enabling band gap tailoring. This decrease is not observed for the other two types with a larger diameter. All structures are found to have magnetic ground states with high magnetic moments indicating the possibility of them being used in spintronics applications.