Thickness dependent charge density wave networks on thin 1T-TaS$_2$

TL;DR

This study uses scanning tunneling microscopy to explore how the charge density wave networks in thin 1T-TaS$_2$ vary with thickness, revealing increased anisotropy and smaller domains as the material becomes thinner.

Contribution

It provides the first detailed analysis of the thickness-dependent anisotropic charge density wave networks in thin 1T-TaS$_2$ using intrinsic sample preparation methods.

Findings

CDW domains become smaller with decreasing thickness.

CDW domains exhibit increased anisotropy in thinner samples.

Intrinsic NCCDW phase observed in thin flakes similar to bulk.

Abstract

We investigate mechanically exfoliated thin 1T-TaS$_2$ with scanning tunneling microscopy at room temperature. Sample preparation without air exposure enables access to intrinsic charge-density-wave (CDW) phases of thin 1T-TaS$_2$. At room temperature, we can observe the expected nearly commensurate CDW (NCCDW) phase on thin flakes similar to bulk 1T-TaS$_2$. Further analysis reveals that the CDW domains in the NCCDW phase become smaller and have more anisotropic shape with decreasing thickness in the range of 8-28 layers. Our findings demonstrate that the anisotropic CDW nature of thin 1T-TaS$_2$ would be crucial to understand its exotic CDW-related phenomena and demand a systematic study on its correlation between the thickness-driven CDW domain anisotropy and the intermediate CDW states in thin 1T-TaS$_2$.