Gold Nanosolenoids Based on Chiral Nanotubes Calculated Using the Relativistic Linearized Augmented Cylindrical Wave Method

Spin-dependent band structures, the electron and spin transport, and the formation of magnetic field in the single-walled chiral gold nanotubes (n 1, n 2) are calculated using a relativistic linearized augmented cylindrical wave method. The helical symmetry of tubules was taken into account when constructing the Hamiltonian and basis functions, the unit cells of any tubule being reduced to one atom. This greatly simplifies the calculations and allows us to present the results in a simple form. There are only 10 filled and 2 half-filled spin-dependent dispersion curves in the band structures of any tubule. All of them have the metal-type electronic structures. In the (5, n 2) and (10, n 2) series calculated, the spin–orbit splitting ΔE S–O values of bands crossing the Fermi level are equal to 0.5 and 0.2 eV, respectively, and the ΔE S–O decreases as one goes to the valence band inner energy states. The numbers N F of crossing points of the bands with the Fermi level coincide almost exactly with the numbers n 1 + n 2 of atomic rows coiling around the tubule’s axis, N F ≈ n 1 + n 2, and a ballistic electron conductivity can be estimated using a simple formula σ ≈ G 0(n 1 + n 2), where G 0 is the conduction quantum. Based on the band structure data for chiral tubes, the cyclic current component and magnetic fields in gold nanosolenoids are calculated. The calculated spin-dependent densities of states for electrons at the Fermi level show that chirality can induce a spin selectivity of electron transport. The spin transport can be controlled by the twisting, stretching, and compression of the tubes.