Structure and Control of Charge Density Waves in Two-Dimensional 1T-TaS2

TL;DR

This paper demonstrates how to manipulate charge density wave states in atomically thin 1T-TaS2 using electrical control, preserving intrinsic properties and enabling continuous tuning of phase transitions.

Contribution

It introduces a method to control CDW phases in 2D 1T-TaS2 via electrical means, with preserved material properties through encapsulation.

Findings

Discommensurations dominate conductance in 2D 1T-TaS2.

Electrical current can precisely tune the discommensuration structure.

Continuous control over the CDW melting transition is achieved.

Abstract

The layered transition metal dichalcogenides host a rich collection of charge density wave (CDW) phases in which both the conduction electrons and the atomic structure display translational symmetry breaking. Manipulating these complex states by purely electronic methods has been a long-sought scientific and technological goal. Here, we show how this can be achieved in 1T-TaS2 in the two-dimensional (2D) limit. We first demonstrate that the intrinsic properties of atomically-thin flakes are preserved by encapsulation with hexagonal boron nitride in inert atmosphere. We use this facile assembly method together with TEM and transport measurements to probe the nature of the 2D state and show that its conductance is dominated by discommensurations. The discommensuration structure can be precisely tuned in few-layer samples by an in-plane electric current, allowing continuous electrical control over the discommensuration-melting transition in 2D.