Disorder-sensitive pump-probe measurements on Nd$_{1.83}$Ce$_{0.17}$CuO$_{4\pm\delta}$ films

TL;DR

This study demonstrates that disorder significantly influences the relaxation dynamics in Nd$_{1.83}$Ce$_{0.17}$CuO$_{4\pm\delta}$ films, with pump-probe measurements revealing disorder-driven changes in electronic excitations and relaxation processes.

Contribution

It provides a detailed analysis linking disorder-induced resistance features to relaxation dynamics using pump-probe spectroscopy in cuprate films.

Findings

Resistance behavior correlates with relaxation parameters across samples.

Disorder affects emergence of new excitations and relaxation channels.

Pump-probe measurements are highly sensitive to disorder effects.

Abstract

We find an unambiguous relationship between disorder-driven features in the temperature dependence of the resistance and the behavior, as functions of the temperature, of the parameters necessary to describe some of the relaxation processes in the photoinduced differential time-resolved reflectivity of three samples of Nd$_{1.83}$Ce$_{0.17}$CuO$_{4\pm\delta}$. The latter, sharing the same Ce content, have been fabricated and annealed ad-hoc in order to differ only for the degree of disorder, mainly related to oxygen content and location, and, consequently, for the temperature dependence of the resistance: two of them present a minimum in the resistance and behave as a superconductor and as a metal, respectively, the third behaves as an insulator. The systematic coherence between the resistance and the relaxation parameters behaviors in temperature for all three samples is absolutely remarkable and shows that pump-probe measurements can be extremely sensitive to disorder as it drives the emergence of new excitations and of the related relaxation channels as in this paradigmatic case.