Ab initio study of iron nanowires encapsulated inside silicon nitride nanotubes

In the present paper, the iron nanowires (containing single Fe atomic chain and Fen nanowire (n=5, 9 and 13)) encapsulated in (8,8) silicon nitride nanotubes (SiNNTs) have been investigated systematically using the first-principles within GGA. For the pristine (8,8) SiNNT, a ferromagnetic ground state is more favorable, and the semiconducting character is observed. After single Fe atom chain encapsulated inside (8,8) SiNNT, two possible configurations are determined depending on the distance from the wire to the tubewall. Furthermore, these two configurations keep high spin-dependent transport and thus can be used in spintronics devices. As for the Fen nanowires encapsulated in (8,8) SiNNTs (Fen@(8,8)), the spin-dependent transport are badly disturbed, but the stabilities of metal wires are reinforced in Fen@(8,8) systems. In particular, an enhanced ferromagnetism is observed after the Fe13 nanowire encapsulated into the (8,8) SiNNT. The results suggest that the Fen@(8,8) systems can be used in the magnetic storage industries.

Net spin charge density (ρup–ρdown) for the Fe9@(8,8) and Fe13@(8,8) systems. Here green (cyan) color shows there is more spin up (down). Figure optionsDownload as PowerPoint slideHighlights
► Pristine armchair (8,8) SiN NT can exist stably.
► The binding processes of all three Fen@(8,8) systems are exothermic.
► Fechain@(8,8) system could be of interest for the use in spin injection.
► An antiparallel alignment is obtained for the free-standing Fe13 nanowire.
► Antiparallel alignment disappears and thus the ferromagnetism is enhanced in Fe13@(8,8).