Effects of edge magnetism and external electric field on energy gaps in multilayer graphene nanoribbons

TL;DR

This study uses first-principles calculations to explore how edge magnetism and external electric fields influence the energy gaps in multilayer graphene nanoribbons with different edge types, alignments, and stacking sequences.

Contribution

It provides new insights into how electric fields and edge configurations affect the electronic properties of multilayer graphene nanoribbons, including gap modulation and magnetic behavior.

Findings

Energy gaps decrease with increasing ribbon width.

Edge alignments and stacking sequences significantly influence band structures.

External electric fields can induce or modulate energy gaps in specific stacking configurations.

Abstract

Using first-principles density-functional theory, we study the electronic structure of multilayer graphene nanoribbons as a function of the ribbon width and the external electric field, applied perpendicular to the ribbon layers. We consider two types of edges (armchair and zigzag), each with two edge alignments (referred to as alpha- and beta-alignments). We show that, as in monolayer and bilayer armchair nanoribbons, multilayer armchair nanoribbons exhibit three classes of energy gaps which decrease with increasing width. Nonmagnetic multilayer zigzag nanoribbons have band structures that are sensitive to the edge alignments and the number of layers, indicating different magnetic properties and resulting energy gaps. We find that energy gaps can be induced in ABC-stacked ribbons with a perpendicular external electric field while in other stacking sequences, the gaps decrease or remain closed as the external electric field increases.