Ultrafast loss of lattice coherence in the light-induced structural phase transition of V$_2$O$_3$

TL;DR

This study investigates how lattice coherence in V$_2$O$_3$ is rapidly lost during a light-induced structural phase transition, revealing non-inertial dynamics and mode coupling effects that differ from traditional coherent phonon behavior.

Contribution

It demonstrates that vibrational coherence is not maintained during the phase transition in V$_2$O$_3$, highlighting the role of disorder and multi-mode coupling in ultrafast lattice dynamics.

Findings

Coherent phonons are generated at low fluence in both phases.

Lattice coherence is lost during the phase transition.

Non-inertial dynamics dominate due to disorder and mode coupling.

Abstract

In solids, the response of the lattice to photo-excitation is often described by the inertial evolution on an impulsively modified potential energy surface which leads to coherent motion. However, it remains unknown if vibrational coherence is sustained through a phase transition, during which coupling between modes can be strong and may lead to rapid loss of coherence. Here we use coherent phonon spectroscopy to track lattice coherence in the structural phase transition of V$_2$O$_3$. In both the low and high symmetry phases unique coherent phonon modes are generated at low fluence. However, coherence is lost when driving between the low and high symmetry phases. Our results suggest non-inertial dynamics dominate during phase transition due to disorder and multi-mode coupling.