Effects of inter-wall interaction and outer-wall disorder on persistent current in a carbon nanotorus

Taken into account inter-wall interaction and outer-wall disorder, we explore the persistent current in a multi-walled carbon nanotorus (MWCNT) within the tight-binding formalism. The calculations show that the inter-wall interaction induces dramatic changes in the energy spectra of both armchair and zigzag MWCNTs such as level splitting, level crossings and/or anticrossings, and even an energy gap opening at the Fermi energy, which leads to a decrease of persistent current and changes in the shape of the flux-dependent current. In the presence of outer-wall disorder, it is found that in the regime of weak disorder, the persistent current decreases with disorder strength, while it increases in the regime of strong disorder. The results show that MWCNTs may be a promising candidate for realizing a new type of surface-doping-like molecule devices.