Persistent currents in multichain mesoscopic rings

We study the persistent current I in finite-width mesoscopic rings within the framework of the tight-binding model. Disorder is introduced via Cauchy-distributed on-site electron energies. The results we have found for the effect of disorder and band-filling are in good agreement with existing theories. However, computer simulations show clear dependence of I on the aspect ratio g = delta(S)/S, with delta(S) being the area of the ring and S that of its hole, which is exhibited as a slight change of the phi(0)-periodicity, and as linear in the enclosed magnetic flux drift of the persistent current. In the case of a 2M-chain ring, the radial and azimuthal structure of the current is briefly discussed. (Author)