Many-body recombination in insulating cuprates

TL;DR

This study investigates ultrafast many-body recombination processes in insulating cuprates using pump-probe spectroscopy, revealing large coefficients and a fluence dependence linked to carrier multiplication.

Contribution

It introduces a model for recombination kinetics in insulating cuprates, highlighting the role of many-body effects and impact ionization in ultrafast dynamics.

Findings

Recombination occurs on femtosecond timescales.

Large trapping and Auger coefficients are observed.

Fluence dependence suggests carrier multiplication.

Abstract

We study the pump-probe response of three insulating cuprates and develop a model for its recombination kinetics. The dependence on time, fluence, and both pump and probe photon energies imply many-body recombination on femtosecond timescales, characterized by anomalously large trapping and Auger coefficients. The fluence dependence follows a universal form that includes a characteristic volume scale, which we associate with the holon-doublon excitation efficiency. This volume varies strongly with pump photon energy and peaks near twice the charge-transfer energy, suggesting that the variation is caused by carrier multiplication through impact ionization.