Low dimensionality in CDW systems leads to anisotropic optical properties, in both equilibrium and non-equilibrium conditions. Here we perform polarized two-color pump probe measurements on a quasi-1D material ZrTe3, in order to study the anisotropic transient optical response in the CDW state. Profound in-plane anisotropy is observed with respect to polarization of probe photons. Below TCDW both the quasi-particle relaxation signal and amplitude mode (AM) oscillation signal are much larger with Epr nearly parallel to a axis (Epr∥a) than for Epr parallel to b axis (Epr∥b). This reveals that Epr∥a signal is much more sensitive to the variation of the CDW gap. Interestingly, the lifetime of the AM oscillations observed with Epr∥b is longer than Epr∥a. Moreover, at high pump fluence where the electronic order melts and the AM oscillations vanish for Epr∥a , the AM oscillatory response still persists for Epr∥b. We discuss possible origins that lead to such unusual discrepancy between the two polarizations.
@article{arxiv.2212.12367,
title = {Highly anisotropic transient optical response of charge density wave order in ZrTe$_3$},
author = {Li Yue and Amrit Raj Pokharel and Jure Demsar and Sijie Zhang and Yuan Li and Tao Dong and Nanlin Wang},
journal= {arXiv preprint arXiv:2212.12367},
year = {2023}
}