Valley-resolved Fano resonance in monolayer transition metal dichalcogenides nanoribbons with attached stubs

TL;DR

This paper demonstrates how quantum interference in monolayer transition metal dichalcogenides nanoribbons with attached stubs can produce valley-polarized Fano resonances, enabling control of valley degrees of freedom for valleytronics applications.

Contribution

It introduces a novel mechanism of valley polarization via valley-resolved Fano resonance caused by quantum interference in stub-engineered nanoribbons.

Findings

Valley-resolved Fano resonances are formed due to intervalley backscattering.

Increasing stubs leads to valley-resolved minigaps in transmission.

Significant valley polarization can be achieved within these minigaps.

Abstract

Valley degree of freedom besides spin is a promising candidate as a carrier of information. Spintronics has come a long way and spin modulation can be realized by quantum interference and spin-orbit coupling effect. However, the control of valley degree of freedom using quantum interference is still a problem to be explored. Here we discover a mechanism of producing valley polarization in a monolayer transition metal dichalcogenides nanoribbon with attached stubs, in which valley-resolved Fano resonance are formed due to the quantum interference of intervalley backscattering. When the quantum interference occurs between the localized states at the edge of the stubs and the continuous channels in the nanoribbon, the transmission dips of Fano effect is valley-polarized. As the number of stubs increases, the valley-polarized transmission dips will split and valley-resolved minigaps are formed by Fano resonance with intervalley backscattering in stub superlattice. When the electron incident energy is in these valley-resolved gaps of the superlattice, even with several stubs, the transmission can have a significant valley polarization. Our finding points to an opportunity to realize valley functionalities by quantum interference.