Carbon nanotube as quantum point contact valley-filter and valley-splitter

TL;DR

This paper demonstrates that strained single-walled carbon nanotubes can function as valley filters and splitters, enabling control over valley-polarized currents through elastic deformation.

Contribution

It reveals how elastic strain in SWNTs can be used to selectively filter and separate valley electrons, a novel approach for valleytronics.

Findings

Strain induces quantized conductance in SWNTs.

Strain enables generation of valley-polarized currents.

Complete valley separation achieved under specific strains.

Abstract

The electrical characteristics of a carbon nanotube can be significantly modified by applying elastic strain. This study focuses on exploring this phenomenon in a single-walled carbon nanotube (SWNT) using tight-binding transport calculations. The results indicate that, under specific strains, an armchair SWNT can act as a filter, separating the two valley electrons K and Kp. Notably, when subjected to deformation, the SWNT exhibits intriguing behaviors, including a quantized conductance profile that varies with the strength of the strain. Consequently, precise control of the width of the quantized plateaus allows for the generation of a polarized valley current. Furthermore, when both K-types are conducted, the strain is demonstrated to completely separate them, directing each K-type through a distinct pathway.