Coherent amplitudon generation in K_0.3MoO_3 through ultrafast inter-band quasi particle decay

TL;DR

This study investigates the generation of coherent amplitudons in the charge density wave material K_0.3MoO_3 using ultrafast spectroscopy, revealing resonant excitation linked to interband plasmon decay and identifying additional collective modes.

Contribution

It demonstrates that coherent amplitudons are generated via resonant decay of photo-excited quasi particles, a novel insight into charge density wave dynamics.

Findings

Coherent amplitudons are resonantly excited at the interband plasmon frequency.

Additional modes are identified as zone-folding modes of the CDW state.

Transient reflectivity shows complex behavior due to multiple excitations.

Abstract

The charge density wave system K_0.3MoO_3 has been studied using variable energy pump-probe spectroscopy, ellipsometry, and inelastic light scattering. The observed transient reflectivity response exhibits quite a complex behavior, containing contributions due to quasi particle excitations, coherent amplitudons and phonons, and heating effects. The generation of coherent amplitudons is discussed in terms of relaxation of photo-excited quasi particles, and is found to be resonant with the interband plasmon frequency. Two additional coherent excitations observed in the transients are assigned to zone-folding modes of the charge density wave state.