Magnetoresistance of metallic perovskite oxide LaNiO$_{3-\delta}$

TL;DR

This study investigates how oxygen deficiency influences the magnetoresistance of LaNiO₃₋δ, revealing a transition from positive to negative MR with increasing δ and temperature-dependent behavior linked to weak localization effects.

Contribution

It provides new insights into the oxygen stoichiometry dependence of magnetoresistance in LaNiO₃₋δ and identifies weak localization as a key mechanism.

Findings

MR changes from positive to negative with increased oxygen deficiency.

Resistivity minima observed at around 20K in more resistive samples.

Negative MR at low temperatures attributed to weak localization effects.

Abstract

We report a study of the magnetoresistance (MR) of the metallic perovskite oxide LaNiO$_{3-\delta}$ as a function of the oxygen stoichiometry $\delta$ ($\delta \leq$ 0.14), magnetic field (H $\leq 6T$) and temperature (1.5K $\leq $ T $\leq $ 25K). We find a strong dependence of the nature of MR on the oxygen stoichiometry. The MR at low temperatures change from positive to negative as the sample becomes more oxygen deficient (i.e, $\delta$ increases). Some of the samples which are more resistive, show a resistivity minima at $T_{min}$ $\approx$ 20K. We find that in these samples the MR is positive at T > $T_{min}$ and negative for T < $T_{min}$. We conclude that in the absence of strong magnetic interaction, the negative MR in these oxides can arise from weak localisation effects.