Reply to "Comment on `Evidence for the immobile bipolaron formation in   the paramagnetic state of the magnetoresistive manganites'"
  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. 
Guo-meng Zhao