Nematic ultrafast dynamics of 2D materials SnS and CDW CuTe

In this talk, I will first introduce the development of ultrafast science and technology.
Generally, the ultrashort laser pulses provide high peak power and high time resolution
for applications in various fields. For example, polarization-dependent femtosecond
spectroscopy at different temperatures determines the nematic dynamics of photoexcited
electrons and phonons in SnS single crystals. The results of this study show that electrons
and coherent acoustic phonons demonstrate significant anisotropy on the ac-plane in the
transition region from 330 K to 430 K, possibly because of strong electron-phonon
coupling (e.g., 1.16 along a-axis at 300 K). However, this in-plane anisotropy weakens
dramatically in the low-temperature (< 330 K) and high-temperature (> 430 K) phases.
These play an important role in anisotropic heat dissipation and charge carrier mobility
in polarization-sensitive optical and optoelectronic devices. Moreover, time-resolved
femtosecond spectroscopy can also study ultrafast charge-density-wave (CDW)
dynamics in CuTe. As a result of this comprehensive survey, the CDW transition
mechanisms are unveiled as a critical scenario for CDW materials. The details will be
discussed in this talk.