Optical creation and temperature stability of the hidden charge density wave state in 1T-TaS_{2-x}Se_{x}

TL;DR

This study uses femtosecond optical spectroscopy to investigate the formation and stability of hidden charge density wave states in 1T-TaS_{2-x}Se_{x}, revealing how Se doping affects the phase transition dynamics and threshold fluence.

Contribution

It demonstrates the optical creation of hidden phases in Se-doped 1T-TaS_{2} and analyzes how Se content influences their stability and excitation threshold.

Findings

Hidden phase can be optically induced up to x=0.6

Threshold fluence increases with Se doping from 1 to 4 mJ/cm^2

Hidden phase stability is only slightly affected by temperature

Abstract

The femtosecond transinet optical spectroscopy is employed to study the relaxation dynamics of the equilibrium and hidden metastable charge-density-wave states in single crystals of 1$T$-TaS$_{2-x}$Se$_{x}$ as a function of the Se doping $x$. Similarly to pristine 1$T$-TaS$_{2}$, the transition to a hidden phase is observed at low temperature after a quench with a single 50~fs laser pulse, in the commensurate Mott phase up to $x=0.6$. The photo-induced hidden-phase formation is accompanied by a notable change in the coherent phonon spectra, and particularly the collective amplitude mode. While the stability of the hidden phase with increased temperatures is only slightly dependent of the Se content the hidden-phase creation-treshold fluence strongly increases with the Se content from 1 to $\sim4$ mJ/cm$^{2}$.