Photoexcited electron dynamics in Kondo insulators and heavy fermions

TL;DR

This study investigates how photoexcited carriers relax in Kondo insulators and heavy fermion metals, revealing temperature-dependent and nonlinear dynamics governed by a hybridization gap, modeled effectively by the Rothwarf-Taylor bottleneck.

Contribution

It demonstrates that carrier relaxation in heavy electron systems is primarily controlled by a hybridization gap, supported by experimental data and Rothwarf-Taylor model analysis.

Findings

Carrier relaxation is strongly temperature dependent.

Nonlinear response observed with varying excitation levels.

Rothwarf-Taylor model accurately describes the dynamics.

Abstract

We have studied the photoexcited carrier relaxation dynamics in the Kondo insulator SmB6 and the heavy fermion metal YbAgCu4 as a function of temperature and excitation level. The dynamic response is found to be both strongly temperature dependent and nonlinear. The data are analyzed with a Rothwarf-Taylor bottleneck model, where the dynamics are governed by the presence of a narrow gap in the density of states near the Fermi level. The remarkable agreement with the model suggests that carrier relaxation in a broad class of heavy electron systems (both metals and insulators) is governed by the presence of a (weakly temperature dependent) hybridization gap.