Light-tunable charge density wave orders in MoTe2 and WTe2 single layers

TL;DR

This study uses density functional theory to show that ultrafast optical pumping can induce and control transient charge density wave orders in monolayer transition metal ditellurides, revealing new light-tunable electronic phases.

Contribution

It demonstrates that ultrafast optical irradiation can stabilize and manipulate hidden charge orders in 2D MoTe2 and WTe2 monolayers, including in insulating phases.

Findings

Ultrafast optical pumping stabilizes multiple transient charge density wave orders.

Light-tunable distortion, periodicity, and electronic structure are observed.

Transient charge ordered metallic phase with 2D diamond clusters is generated.

Abstract

By using constrained density functional theory modeling, we demonstrate that ultrafast optical pumping unveils hidden charge orders in group VI monolayer transition metal ditellurides. We show that irradiation of the insulating 2H phases stabilizes multiple transient charge density wave orders with light-tunable distortion, periodicity, electronic structure and bandgap. Moreover, optical pumping of the semimetallic 1T' phases generates a transient charge ordered metallic phase composed of 2D diamond clusters. For each transient phase we identify the critical fluence at which it is observed and the specific optical and Raman fingerprints to directly compare with future ultrafast pump-probe experiments. Our work demonstrates that it is possible to stabilize charge density waves even in insulating 2D transition metal dichalcogenides by ultrafast irradiation.