Modeling of Nanoscale Electromagnets Based on Gold Finite Nanosolenoids

Magnetic fields generated by the nanosolenoids based on the (5, 3) and (10,7) gold nanotubes (AuNTs) 12–600 Å long with numbers of Au atoms 20–2000 are calculated. The electron energy levels of the finite length tubules were determined using the linearized augmented cylindrical waves method with Born–von Karman cyclic boundary conditions and on account of a helical symmetry of the AuNTs. Using these data, the numbers of conducting channels NF and the low-temperature ballistic electron currents in the finite AuNTs are determined, and finally, the magnetic fields B of the gold nanosolenoids are obtained. Due to the increase in the number of conduction channels with the increase in the length of the tubes, the internal magnetic field gradually increases from 1.6 T/V in a tubule with L = 12 Å up to 12 T/V in a tube with L = 600 Å, slowly approaching the magnetic field of 14 T/V of the infinite (5, 3) AuNT. At a distance of 5 Å from the ends of the tubes (near z = L/2 – 5 Å), this field decreases rapidly, halving at z = L/2 and almost zeroing near z = L/2 + 5 Å. The field from the outside of the tubes is weak but not zero as in the infinite tubule. It is minimal at z = 0 and reaches a maximum at the edge of the AuNTs, where it is about 3–4 times less than the internal field. These results pave the way for a more realistic design of the nanosolenoids.