Stability and magnetic properties of Fe encapsulating in silicon nanotubes

Using all-electron density functional theory with gradient correction, we have investigated the stability of quasi-one-dimensional tubular nanostructures by stacking the pentagonal FeSi10 prism and hexagonal FeSi12 prism along their axes. The local magnetic moments on Fe atoms in finite hexagonal nanotubes increase linearly with tube length, whereas the magnetism in most finite pentagonal nanotubes are quenched owing to the charge transfer and strong hybridization between 4s and 3d states of Fe and 3s and 3p states of Si. The infinite hexagonal nanotube with stoichiometry of FeSi6 is found to be ferromagnetic with magnetic moment per Fe atom comparable to the bulk value. Both pentagonal and hexagonal nanotubes exhibit metallic behaviour in the case of finite and infinite structures. These theoretical results provide useful information for application of spintronics and other nanodevices