MoS_2 as an ideal material for valleytronics: valley-selective circular dichroism and valley Hall effect

TL;DR

This paper demonstrates through first principles calculations that monolayer MoS_2 exhibits valley-selective circular dichroism, valley polarization, and the valley Hall effect, making it an ideal material for valleytronic applications.

Contribution

It provides the first demonstration that monolayer MoS_2 can achieve valley polarization and valley Hall effect, highlighting its potential for valleytronic devices.

Findings

Monolayer MoS_2 exhibits valley-selective circular dichroism.

Valley polarization and valley Hall effect are demonstrated in MoS_2.

MoS_2 is identified as an ideal material for valleytronics.

Abstract

A two-dimensional honeycomb lattice harbors a pair of inequivalent valleys in the k-space electronic structure, in the vicinities of the vertices of a hexagonal Brillouin zone, K}$_{\pm}$. It is particularly appealing to exploit this emergent degree of freedom of charge carriers, in what is termed "valleytronics", if charge carrier imbalance between the valleys can be achieved. The physics of valley polarization will make possible electronic devices such as valley filter and valley valve, and optoelectronic Hall devices, all very promising for next-generation electronic and optoelectronic applications. The key challenge lies with achieving valley imbalance, of which a convincing demonstration in a two-dimensional honeycomb structure remains evasive, while there are only a handful of examples for other materials. We show here, using first principles calculations, that monolayer MoS_2, a novel two-dimensional semiconductor with a 1.8 eV direct band gap, is an ideal material for valleytronics by valley- selective circular dichroism, with ensuing valley polarization and valley Hall effect.