Predicting interface and spin states in armchair graphene nanoribbon junctions

TL;DR

This paper provides a theoretical framework for predicting interface and spin states in armchair graphene nanoribbon junctions, emphasizing the roles of width differences, bonding, and strain in determining localized electronic and magnetic properties.

Contribution

It introduces new rules for predicting interface states and magnetic moments based on structural parameters and strain effects in graphene nanoribbon junctions.

Findings

Interface states depend on width differences and bonding configurations.

Strain influences topological properties and interface states.

Magnetic behavior is linked to localized states at the junction.

Abstract

We present a theoretical analysis of interface states emerging at junctions between armchair graphene nanoribbons of varying widths. By exploring diverse width combinations and junction geometries, we demonstrate that predicting the precise number of interface states requires considerations beyond the topological classification alone; specifically, the width differences and bonding configuration at the interface play crucial roles. For junctions involving ribbons with small gaps, we further examine how an applied strain affects their topological properties and, consequently, the interface states formed. The spin states at these junctions are investigated using the mean-field Hubbard model, revealing how the magnetic behavior at the interface depends on the number of localized states present. These results are summarized in a series of ``rules of thumb" to predict the number of localized states and the magnetic moment at the junction. Our findings contribute to understanding and engineering localized states in graphene-based devices, providing guidelines for manipulating electronic and magnetic properties through structural design.