Infrared response of ordered polarons in layered perovskites

TL;DR

This study investigates the infrared absorption spectra of layered perovskites with ordered polarons, revealing how charge ordering influences their vibrational and electronic properties.

Contribution

It provides new insights into the infrared response of ordered polarons in layered perovskites, highlighting the effects of charge ordering on vibrational modes and conductivity.

Findings

Polaron localization suppresses low-energy conductivity.

Charge ordering causes splitting of vibrational modes.

Distinct effects observed in different oxide compounds.

Abstract

We report on the infrared absorption spectra of three oxides where charged superlattices have been recently observed in diffraction experiments. In La$_{1.67}$Sr$_{0.33}$NiO$_4$, polaron localization is found to suppress the low-energy conductivity through the opening of a gap and to split the $E_{2u}$-$A_{2u}$ vibrational manifold of the oxygen octahedra. Similar effects are detected in Sr$_{1.5}$La$_{0.5}$MnO$_4$ and in La$_2$NiO$_{4+y}$, with peculiar differences related to the type of charge ordering.