Fano Resonances in Mismatched C$_3$N Nanoribbon Junctions

TL;DR

This study investigates Fano resonances in mismatched C$_3$N nanoribbon junctions, revealing how edge and interface states interact and can be tuned via external gating to control quantum interference effects.

Contribution

It demonstrates that geometrical mismatch and external gating can be used to engineer and control Fano resonances in C$_3$N nanoribbon junctions.

Findings

Fano resonances arise from coupling between edge and localized interface states.

External gate potential can selectively shift edge state energies.

The number and shape of resonances depend on junction mismatch.

Abstract

Mismatched junctions formed by two C$_3$N zigzag nanoribbons of different widths provide a useful setting for studying quantum interference effects involving edge state transport. A crucial ingredient for this interference to appear is, besides the presence of edge states, the formation of localized interface states at the mismatched interface of the junction. At the level of a tight-binding model it is shown that, by means of an external gate potential, one of the edge state energy bands can selectively be shifted into the energy range of the localized interface states. The resulting coupling between the edge and localized interface states gives rise to pronounced Fano resonances in both the density of states and the transmission spectrum with line shapes well described by the canonical Fano formula. Furthermore, it is found that the geometrical mismatch of the junction not only determines the number of resonances but also the energetic orientation of their asymmetric line shapes. These results identify mismatched C$_3$N nanojunctions as a tunable and robust platform for engineering interference-driven transport.