Steering the current flow in twisted bilayer graphene

TL;DR

This paper demonstrates a method to control and steer electron current flow in twisted bilayer graphene devices, enabling potential applications in twistronics and valleytronics by exploiting band structure and twist angle effects.

Contribution

It introduces a novel approach to steer current in TBLG using twist angle and band structure manipulation, advancing control in nanoelectronic devices.

Findings

Current can be directed to opposite edges by reversing twist angle or injection band.

Steering angle exceeds the twist angle and is robust across parameters.

The current is partially valley polarized due to band shape dependence.

Abstract

A nanoelectronic device made of twisted bilayer graphene (TBLG) is proposed to steer the direction of the current flow. The ballistic electron current, injected at one edge of the bottom layer, can be guided predominantly to one of the lateral edges of the top layer. The current is steered to the opposite lateral edge, if either the twist angle is reversed or the electrons are injected in the valence band instead of the conduction band, making it possible to control the current flow by electric gates. When both graphene layers are aligned, the current passes straight through the system without changing its initial direction. The observed steering angle exceeds well the twist angle and emerges for a broad range of experimentally accessible parameters. It is explained by the trigonal shape of the energy bands beyond the van Hove singularity due to the Moir\'e interference pattern. As the shape of the energy bands depends on the valley degree of freedom, the steered current is partially valley polarized. Our findings show how to control and manipulate the current flow in TBLG. Technologically, they are of relevance for applications in twistronics and valleytronics.