Quasi-bound states and Fano effect in T-shaped graphene nanoribbons

TL;DR

This paper investigates the formation of quasi-bound states in T-shaped graphene nanoribbons and how these states influence electron transport via the Fano effect, revealing specific geometric conditions for their existence.

Contribution

It systematically analyzes the conditions for quasi-bound states in T-shaped graphene nanoribbons and their impact on transport properties, highlighting the role of geometric parameters.

Findings

Quasi-bound states occur when the sidearm width is about half of the lead width.

These states are localized in the sidearm with small continuum components.

They significantly affect transport via the Fano effect, but not between the lead and the sidearm.

Abstract

We study the quasi-bound state and the transport properties in the T-shaped graphene nanoribbon consisting of a metallic armchair-edge ribbon connecting to a zigzag-edge sidearm. We systematically study the condition under which there are quasi-bound states in the system for a wide range of the system size. It is found that when the width of the sidearm is about half of the width of the armchair leads, there is a quasi-bound state trapped at the intersection of the T-shape structure. The quasi-bound states are truly localized in the sidearm but have small continuum components in the armchair leads. The quasi-bound states have strong effect on the transport between the armchair leads through the Fano effect, but do not affect the transport between the armchair lead and the sidearm.