Reply to "Comment on `Evidence for the immobile bipolaron formation in the paramagnetic state of the magnetoresistive manganites'"

TL;DR

This paper defends a model where immobile bipolarons and thermally-excited small polarons explain oxygen-isotope effects in manganites, countering misunderstandings and incorrect reproductions in a recent comment.

Contribution

It clarifies and supports the original theoretical model explaining electrical transport in manganites, addressing and correcting misconceptions from a recent critique.

Findings

The isotope effects are inconsistent with bipolaron hopping alone.

The original model accurately explains the observed transport properties.

Counterarguments show the critique's model is incompatible with experimental data.

Abstract

Zhao et al. [Phys. Rev. B 62, R11 949 (2000)] reported studies of the oxygen-isotope effects on the intrinsic resistivity and thermoelectric power in the paramagnetic state of several ferromagnetic manganites. The isotope effects on the intrinsic electrical transport properties are not consistent with a simple small-polaron hopping mechanism, but can be well explained by a model where there coexist immobile bipolarons and thermally-excited small polarons. Recently, Banerjee et al. [Phys. Rev. B 68, 186401 (2003)] wrote a Comment on our paper, where they misunderstood our theoretical model, erroneously thinking that we explain the electrical transport in the paramagnetic state as due to bipolaron hopping. They confuse large polarons with small bipolarons, use incorrect conditions for bipolaron formation, and even incorrectly reproduce our data. We show that the model used in the Comment is inconsistent with any features of the observed oxygen-isotope effects. More evidence is provided to support the theoretical model used in our original paper.