First-Principles Study of Electron-Conduction Properties of Helical Gold Nanowires

Multishell helical gold nanowires (HGNs) suspended between semi-infinite electrodes are found to exhibit peculiar electron-conduction properties by first-principles calculations based on the density functional theory. Our results that the numbers of conduction channels in the HGNs and their conductances are smaller than those expected from a single-atom row nanowire verify the recent experiment. In addition, we obtained a more striking result that, in the cases of thin HGNs, distinct magnetic fields are induced by the electronic current helically flowing around the shells. This finding indicates that the HGNs can be good candidates for nanometer-scale solenoids.

Figure 1

Isosurfaces of channel electron distributions of single-atom row and 7-1 nanowires. (a) The first channel of the single-atom row nanowire, (b) the first channel, (c) the third channel, and (d) the fourth channel of the 7-1 nanowire. The states incident from the left electrode are shown. The yellow and green spheres represent the atoms in the outer and inner shells, respectively. The rectangular parallelepipeds at both the edges of the nanowires are jellium electrodes.

Figure 2

Induced magnetic flux density per bias voltage. (a) The 7-1, (b) 11-4, and (c) 15-8-1 nanowires. The green, yellow, and gray spheres represent the atoms in the innermost, second, and third shells, respectively. The broken lines are the edges of the jellium electrodes.