Oxygen isotope effects in high-quality thin films of manganites: Quantitative constraints on the physics of manganites

TL;DR

This study investigates how oxygen isotope substitution affects transport properties in high-quality manganite thin films, providing quantitative insights into the underlying physics of these complex oxides.

Contribution

It offers the first detailed quantitative analysis of oxygen isotope effects on resistivity in manganite thin films, constraining theoretical models of their physics.

Findings

Resistivity parameters depend strongly on oxygen isotope mass.

Resistivity below 80 K follows a specific temperature dependence.

Oxygen isotope substitution increases resistivity parameters by about 15%.

Abstract

Oxygen isotope effects on the transport properties have been studied in high-quality epitaxial thin films of La_{0.75}Ca_{0.25}MnO_{3} and Nd_{0.7}Sr_{0.3}MnO_{3}. In the paramagnetic state, the resistivity can be well fitted by \rho (T) = (A/\sqrt{T})\exp(E_{\rho}/k_{B}T) with the parameters A and E_{a} depending strongly on the oxygen isotope mass. The resistivity below 80 K almost perfectly follows \rho = \rho_{o}+ B\omega_{s}/\sinh^{2}(\hbar\omega_{s}/2k_{B}T) with \hbar\omega_{s}/k_{B} \sim 100 K. Both \rho_{o} and B increase by about 15(3)% upon raplacing $^{16}$O by $^{18}$O. The results provide quantitative constraints on the basic physics of manganites.