Chiral currents in gold nanotubes

Results are presented for the electron current in gold chiral nanotubes (AuNTs). Starting from the band structure of (4,3) and (5,3) AuNTs, we find that the magnitude of the chiral currents are greater than those found in carbon nanotubes. We also calculate the associated magnetic flux inside the tubes and find this to be higher than the case of carbon nanotubes. Although (4,3) and (5,3) AuNTs carry transverse momenta of similar magnitudes, the low-bias magnetic flux carried by the former is far greater than that carried by the latter. This arises because the low-bias longitudinal current carried by a (4,3) AuNT is significantly smaller than that of a (5,3) AuNT.

Figure 1

(Color online) A (4,3) AuNT and a triangular sheet showing a (4,3) chiral vector. Periodic boundary conditions make the two lattice points at the ends of $\mathbf{C}$ vector identical. The $\mathbf{T}$ vector shows the unit cell of the AuNT. The thin red lines show the first, second, and third nearest neighbors of the highlighted lattice point.

Figure 2

(Color online) The black dashed lines show the DFT calculated band structure of the perfect folded AuNT. The red curves show the fitted tight binding band structure. $E_F$ is the Fermi energy.

Figure 3

(Color online) The top, second, and third rows show chiral and longitudinal velocities and their ratios for each miniband of the (4,3) and (5,3) AuNTs. The red curves show those chiral velocity values belonging to right-moving electrons. Those of left-moving electrons are shown by dotted curves. The thick black curve shows the sum of the corresponding red curves. and the chiral velocities (red lines) for each channel. The velocities are in units of average Fermi velocity $v_F$ of the triangular lattice sheet. The capital letters label individual open channels.

Figure 4

(Color online) The forces against bias voltage. The red curve belongs to (4,3) AuNT and the blue curve belongs to the (5,3) AuNT.

Figure 5

(Color online) The magnetic field against bias voltage. The red curves belongs to (4,3) AuNT and the blue curve belongs to the (5,3) AuNT.