Comment on 'Local structure, magnetization and Griffiths phase of self-doped La1-xMnO3+δ manganites'

In a recent paper [1], Ulyanov et al. reported data on structure and magnetic properties of the series of polycrystalline self-doped La-1 xMnO3+delta manganite ceramics. In particular, the authors claimed that magnetic behavior of the samples studied exhibits Griffiths-like features above their Curie temperatures. It is suggested in the comment that such a claim seems to be doubtful. We emphasize that idealized thermodynamic model of 'Griffiths phase' is inapplicable for description of the paramagnetic state in doped manganites in general. As to the La-1 xMnO(3+) series, the downturn anomalies on inverse magnetization versus temperature dependences ('Griffiths-like features') appear, most likely, due to the presence of magnetic polarons, which concentration increases upon cooling towards the Curie temperature. (C) 2014 Elsevier B. V. All rights reserved.