QUANTUM TRANSPORT IN TOPOLOGICAL MESOSCOPIC RING STRUCTURES

We have studied the electronic: transport properties of various topolo gical mesoscopic rings which consist of several variable-size chains j oined at their ends to form ideal single-channel leads. An enhancement of the transmission coefficient is obtained when the chain lengths ar e randomly distributed, due to the suppression of interchain interfere nce, and, in the presence of magnetic flux, periodic magnetoconductanc e oscillations are also shown. A single impurity changes the magneto-o scillation pattern drastically, while for more impurities placed at ra ndom the periodic magnetoconductance oscillations survive. Finally, th e introduction of a transverse link between the chains destroys the br idge-cc shape of the transmission versus energy curves obtained in the absence of such a link.