Ultrafast Collective Dynamics in the Charge-Density-Wave Conductor K$_{0.3}$MoO$_{3}$

TL;DR

This study uses femtosecond pump-probe spectroscopy to reveal ultrafast collective charge-density wave excitations in K$_{0.3}$MoO$_{3}$ and K$_{0.33}$MoO$_{3}$, demonstrating momentum-resolved optical detection of these phenomena.

Contribution

It introduces a novel application of time-resolved optical techniques to achieve momentum resolution of collective excitations in strongly correlated electron systems.

Findings

Observation of linear gapless dispersion for transverse phasons

Pronounced anisotropy in K$_{0.33}$MoO$_{3}$

Detection of a 1.67 THz amplitude mode at 30 K

Abstract

Low-energy coherent charge-density wave excitations are investigated in blue bronze (K$_{0.3}$MoO$_{3}$) and red bronze (K$_{0.33}$MoO$_{3}$) by femtosecond pump-probe spectroscopy. A linear gapless, acoustic-like dispersion relation is observed for the transverse phasons with a pronounced anisotropy in K$_{0.33}$MoO$_{3}$. The amplitude mode exhibits a weak (optic-like) dispersion relation with a frequency of 1.67 THz at 30 K. Our results show for the first time that the time-resolved optical technique provides momentum resolution of collective excitations in strongly correlated electron systems.Low-energy coherent charge-density wave excitations are investigated in blue bronze (K$_{0.3}$MoO$_{3}$) and red bronze (K$_{0.33}$MoO$_{3}$) by femtosecond pump-probe spectroscopy. A linear gapless, acoustic-like dispersion relation is observed for the transverse phasons with a pronounced anisotropy in K$_{0.33}$MoO$_{3}$. The amplitude mode exhibits a weak (optic-like) dispersion relation with a frequency of 1.67 THz at 30 K. Our results show for the first time that the time-resolved optical technique provides momentum resolution of collective excitations in strongly correlated electron systems.