# Incommensurate Chiral CDW in $1T$-VSe$_2$

## TL;DR

This study reveals the presence of incommensurate chiral charge-density waves in $1T$-VSe$_2$, characterized by lower rotational symmetry and a kagome lattice structure, confirmed through STM and optical measurements.

## Contribution

The paper demonstrates the existence of chiral CDWs in $1T$-VSe$_2$ with unique symmetry properties and lattice arrangements, expanding understanding of chiral phenomena in layered materials.

## Key findings

- CDW intensities differ along triple-q directions
- CDW peaks form a kagome lattice
- Chirality reflected in Friedel oscillations

## Abstract

We have investigated the chiral charge-density wave (CDW) in $1T$-VSe$_2$ using scanning tunneling microscopy (STM) measurements and optical polarimetry measurements. With the STM mesurements, we revealed that the CDW intensities along each triple-$q$ directions are different. Thus the rotational symmetry of $1T$-VSe$_2$ is lower than that in typical two-dimentional triple-$q$ CDWs. We found that the CDW peaks form a kagome lattice rather than a triangular lattice. The Friedel oscillations have the chirality and the periodicity reflected properties of the background CDW. With the optical measurements in $1T$-VSe$_2$, we also observed a lower rotational symmetry with the polarization dependence of the transient reflectivity variation, which is consistent with the STM result on a microscopic scale. Both $1T$-TiSe$_2$ and $1T$-VSe$_2$ show chiral CDWs, which implies that such waves are usual for CDWs with the condition $H_\mathrm{CDW} \equiv q_{1}\cdot(q_{2} \times q_{3}) \neq0$.