Photo-induced Dynamics and Momentum Distribution of Chiral Charge Density Waves in 1T-TiSe$_{2}$

TL;DR

This study investigates how circularly polarized light can manipulate chiral charge density waves in 1T-TiSe$_{2}$, revealing differences in CDW suppression and domain expansion, and demonstrating a new method for detecting chirality dynamics.

Contribution

It provides the first direct observation of photoinduced chirality dynamics in 1T-TiSe$_{2}$ using time-resolved X-ray diffraction with circularly polarized lasers.

Findings

20% difference in CDW suppression between polarizations

Momentum-resolved circular dichroism linked to chirality domains

Immediate increase in CDW correlation length upon laser pumping

Abstract

Exploring the photoinduced dynamics of chiral states offers promising avenues for advanced control of condensed matter systems. Photoinduced or photoenhanced chirality in 1T-TiSe$_{2}$ has been suggested as a fascinating platform for optical manipulation of chiral states. However, the mechanisms underlying chirality training and its interplay with the charge density wave (CDW) phase remain elusive. Here, we use time-resolved X-ray diffraction (tr-XRD) with circularly polarized pump lasers to probe the photoinduced dynamics of chirality in 1T-TiSe$_{2}$. We observe a notable ($\sim$20%) difference in CDW intensity suppression between left- and right-circularly polarized pumps. Additionally, we reveal momentum-resolved circular dichroism arising from domains of different chirality, providing a direct link between CDW and chirality. An immediate increase in CDW correlation length upon laser pumping is detected, suggesting the photoinduced expansion of chiral domains. These results both advance the potential of light-driven chirality by elucidating the mechanism driving chirality manipulation in TiSe$_2$, and they demonstrate that tr-XRD with circularly polarized pumps is an effective tool for chirality detection in condensed matter systems.