# Hybridization dynamics in CeCoIn5 revealed by ultrafast optical spectroscopy

## TL;DR

This study uses ultrafast optical spectroscopy to explore the hybridization dynamics and collective excitations in the heavy fermion compound CeCoIn5, revealing hybridization fluctuations, gap opening, and a potential density wave.

## Contribution

It provides new insights into the hybridization fluctuations and collective modes in CeCoIn5, advancing understanding of heavy fermion behavior through ultrafast spectroscopy.

## Key findings

- Hybridization fluctuations occur between 120 K and 55 K.
- Anomalous phonon softening and damping reduction below T*.
- Discovery of an 8 meV collective mode possibly linked to an unconventional density wave.

## Abstract

We investigate the quasiparticle dynamics in the prototype heavy fermion CeCoIn$_5$ using ultrafast optical pump-probe spectroscopy. Our results indicate that this material system undergoes hybridization fluctuations before full establishment of the heavy electron coherence, as the temperature decreases from $\sim$120 K ($T^\dagger$) to $\sim$55 K ($T^*$ ). We reveal that the observed anomalous phonon softening and damping reduction below $T^*$ are directly associated with opening of an indirect hybridization gap. We also discover a distinct collective mode with an energy of $\sim$8 meV, which may be the experimental evidence of the predicted unconventional density wave. Our observations provide critical informations for understanding the hybridization dynamics in heavy fermion materials.