Driving electronic features of twisted bilayer zigzag-graphene nanoribbons

TL;DR

This paper investigates how twisted bilayer zigzag-graphene nanoribbons exhibit unique localized edge states and transport properties, with twist angle serving as a key control parameter for electronic responses and beam splitter phenomena.

Contribution

It introduces a detailed tight-binding model to analyze the influence of stacking symmetry, twist angle, and ribbon width on electronic and transport properties of twisted bilayer graphene nanoribbons.

Findings

Localized states are linked to non-equivalent edge sites.

Twist angle significantly controls transport responses.

Observed beam splitter phenomena in four-terminal devices.

Abstract

Novel physical properties have been reported recently by stacking graphene-like systems in different configurations. Here, we explore the nature of emergent localized states at the edges of twisted bilayer graphene nanoribbons. Based on an extended tight-binding Hamiltonian, which includes hopping energy within a wide atomic neighborhood, we investigate the nature of the electronic states responsible for the transport along the four graphene nanoribbon terminals. The emphasis is on discussing the role of the stacking region symmetries, the twisted angle between the crossed zigzag nanoribbons, and also the width of the ribbons in the electronic and transport responses of the four terminals. Our findings show a direct connection between the number of non-equivalent sites on the edge of the stacking region and the localized states, in accordance with reported scanning tunneling spectroscopy measurements. Within the parameters explored, the twist angle was revealed to be the most powerful tool to control transport responses in the investigated 4-terminal devices, including special electronic beam splitter phenomena.