Signatures of polaronic excitations in quasi-one-dimensional LaTiO$_{3.41}$

TL;DR

This study investigates the optical properties of quasi-one-dimensional LaTiO$_{3.41}$, revealing signatures of polaronic excitations and electron-phonon interactions that suggest a phase transition and complex charge dynamics.

Contribution

It provides experimental evidence of polaronic excitations in LaTiO$_{3.41}$ and links optical features to electron-phonon coupling in a quasi-one-dimensional system.

Findings

Observation of phase transition signatures in optical modes

Detection of a midinfrared band consistent with polaron models

Correlation between electron-phonon coupling and dc conductivity behavior

Abstract

The optical properties of quasi-one-dimensional metallic LaTiO$_{3.41}$ are studied for the polarization along the $a$ and $b$ axes. With decreasing temperature modes appear along both directions suggestive for a phase transition. The broadness of these modes along the conducting axis might be due to the coupling of the phonons to low-energy electronic excitations across an energy gap. We observe a pronounced midinfrared band with a temperature dependence consistent with (interacting) polaron models. The polaronic picture is corroborated by the presence of strong electron-phonon coupling and the temperature dependence of the dc conductivity.