Half-metallicity in aluminum-doped zigzag silicene nanoribbons

Abstract

The spin-dependent electronic structures of aluminum-(Al) doped zigzag\nsilicene nanoribbons (ZSiNRs) are investigated by first-principles\ncalculations. When ZSiNRs are substitutionally doped by a single Al atom on\ndifferent sites in every three primitive cells, they become half-metallic in\nsome cases, a property that can be used in spintronic devices. More\ninterestingly, spin-down electrons can be transported at the Fermi energy when\nthe Al atom is placed on the sub-edge site. In contrast, spin-up electrons can\nbe transported at the Fermi energy when the ZSiNRs are doped on sites near\ntheir center. The magnetic moment on edge is considerably suppressed if the Al\natom is doped on edge or near-edge sites. Similar results are obtained for a\nphosphorus-(P) and boron-(B) doped ZSiNR. When two or more Si atoms are\nreplaced by Al atoms, in general the half-metallic behavior is replaced by a\nmetallic, spin gapless semiconducting or semiconducting one. When a line of six\nSi atoms, along the ribbon's width, are replaced by Al atoms, the spin\nresolution of the band structure is suppressed and the system becomes\nnonmagnetic.\n