Transient terahertz photoconductivity of insulating cuprates

TL;DR

This study investigates the transient terahertz photoconductivity in insulating cuprates, revealing details about photocarrier dynamics, mobility, and recombination processes in copper oxide planes.

Contribution

It provides a detailed phenomenology of photocarrier transport in insulating cuprates, including measurements of mobility and decay kinetics, which were previously not well characterized.

Findings

Photoconductivity saturates with fluence

Photocarriers exhibit multiple picosecond decay times

Intrinsic photocarrier mobility is estimated at 0.6-0.7 cm^2/Vs

Abstract

We establish a detailed phenomenology of photocarrier transport in the copper oxide plane by studying the transient terahertz photoconductivity of Sr$_2$CuO$_2$Cl$_2$ and YBa$_2$Cu$_3$O$_6$. The peak photoconductivity saturates with fluence, decays on multiple picosecond timescales, and evolves into a state characterized by activated transport. The time dependence shows little change with fluence, indicating that the decay is governed by first-order recombination kinetics. We find that most photocarriers make a negligible contribution to the dc photoconductivity, and we estimate the intrinsic photocarrier mobility to be 0.6-0.7 cm$^2$/V s at early times, comparable to the mobility in chemically doped materials.