Valley splitting in the transition-metal dichalcogenides monolayer via atoms adsorption

TL;DR

This study demonstrates that adsorbing transition-metal atoms on monolayer transition-metal dichalcogenides induces valley splitting via local magnetic moments, enabling tunable control of valley degeneracy for potential spin-valleytronic devices.

Contribution

It reveals a method to induce and tune valley splitting in monolayer TMDs through atom adsorption and magnetic field control, advancing valleytronics.

Findings

Adsorption of transition-metal atoms introduces local magnetic moments.

Zeeman effect from magnetic moments lifts valley degeneracy.

Valley splitting can be tuned continuously by external magnetic fields.

Abstract

In this letter we study the valley degeneracy splitting of the transition-metal dichalcogenides monolayer by first-principles calculations. The local magnetic moments are introduced into the system when the transition-metal atoms are adsorbed to the monolayer surface. Zeeman effect arising from the local magnetic moment at transition-metal atom sites lifts the valley degeneracy. Anomalous charge, spin and valley Hall Effects can be accessed due to valley splitting when we can only excite carriers of one valley. The valley splitting depends on the direction of magnetization and thus can be tuned continuously by an external magnetic field. This tunable valley splitting offers a practical avenue for exploring device paradigms based on the spin and valley degrees of freedom.