# Generalized waveguide approach to tight-binding wires: Understanding large vortex currents in quantum rings - Condensed Matter > Mesoscale and Nanoscale Physics

Abstract: We generalize the quantum waveguide approach to H\-uckel or tight-bindingmodels relevant to unsaturated $\p$ molecular devices. A Landauer-like formulafor the current density through {\em internal} bonds is also derived whichallows for defining a local conductance. The approach is employed to studyinternal circular currents in two-terminal rings. We show how to predict theoccurrence and the nature of large vortex currents in coincidence withvanishingly small currents in the leads. We also prove a remarkably simpleformula for the onset of a vortex regime.

Author: Gianluca Stefanucci, Enrico Perfetto, Stefano Bellucci, Michele Cini

Source: https://arxiv.org/