A dynamical stability limit for the charge density wave in K0.3MoO3

TL;DR

This study investigates the stability limit of the charge density wave in K0.3MoO3 under various excitations, revealing a universal threshold for its melting linked to lattice displacement, akin to the Lindemann criterion.

Contribution

It demonstrates a universal stability limit for charge density waves, connecting lattice dynamics to a critical excitation threshold across different excitation methods.

Findings

Charge density wave melts abruptly at a critical lattice displacement.

Universal curve collapses data from different excitation types.

Mode damping and frequency soften above the threshold.

Abstract

We study the response of the one-dimensional charge density wave in K0.3MoO3 to different types of excitation with femtosecond optical pulses. We compare the response to direct excitation of the lattice at mid-infrared frequencies with that to the injection of quasi-particles across the low-energy charge density wave gap and to charge transfer excitations in the near infrared. For all three cases, we observe a fluence threshold above which the amplitude-mode oscillation frequency is softened and the mode becomes increasingly damped. We show that all the data can be collapsed onto a universal curve in which the melting of the charge density wave occurs abruptly at a critical lattice excursion. These data highlight the existence of a universal stability limit for a charge density wave, reminiscent of the empirical Lindemann criterion for the stability of a crystal lattice.