A light-induced charge order mode in a metastable cuprate ladder

TL;DR

This study observes a light-induced, metastable charge order mode in a cuprate ladder, revealing a regime of dynamic charge fluctuations and itinerant correlated carriers, advancing understanding of light-controlled electronic states.

Contribution

It reports the discovery of a light-induced charge order mode and associated collective excitations in a cuprate ladder, highlighting a new dynamic regime of fluctuating charge order.

Findings

Detected a gapless collective excitation dispersing from the charge-order wavevector.

Observed partial melting of equilibrium charge order under near-infrared excitation.

Revealed a regime where correlated carriers become itinerant at finite momentum.

Abstract

We report the observation of an emergent charge order mode in the optically-excited cuprate ladder Sr$_{14}$Cu$_{24}$O$_{41}$. Near-infrared light in the ladder plane drives a symmetry-protected electronic metastable state together with a partial melting of the equilibrium charge order. Our time-resolved resonant inelastic x-ray scattering measurements at the upper Hubbard band reveal a gapless collective excitation dispersing from the charge-order wavevector up to 0.8 eV with a slope on the order of the quasiparticle velocity. These findings reveal a regime where correlated carriers acquire itinerant character at finite momentum, and charge order becomes dynamically fluctuating, offering a platform to explore light-induced pairing instabilities.