Structural, electronic and magnetic properties of GaN nanotubes filled with nickel nanowires

We present a systemic study of the structural, electronic and magnetic properties of Nin nanowires (n = 5, 9, 13) encapsulated in gallium nitride nanotubes (GaNNTs) using the first-principles calculations. We find that the initial shapes (quadratic-prismatic Ni nanowire and cylindrical (8,8) GaNNT) are preserved without any visible changes for the Ni5@(8,8) and Ni9@(8,8) systems, while for the Ni13@(8,8) system not only a quadraticlike cross-section shape is formed for nanotube but also an anticlockwise rotation about common axis is taken place for nanotube with respect to the nanowire. For both the free-standing Nin nanowires and Nin@(8,8) systems, the magnetic moment increases with decreasing the number n of the Ni atoms in per unit cell and increases as going from the core Ni atom to the outermost shell Ni atom for certain n. Both the total density of states (DOS) and charge density analyses show that the spin polarization and the magnetic moment of Nin@(8,8) systems come solely from the Ni nanowires. Not much decreasing in the spin polarization and the magnetic moment for the Nin@(8,8) systems with respect to the corresponding free-standing Nin nanowires imply the Nin@(8,8) systems can be applied to the circuits that demand preferential transport of electrons with a specific spin.