On peculiarities of the electron transport in doped manganites

A systematic experimental study of the temperature dependences of the resistivity and thermopower, S, in hole- and electron-doped manganites of the ReMnO3 (Re = La, Ce) systems doped by strontium in a wide range of content was performed. The main specific features of the thermopower behavior at temperatures both below and above the temperature of the magneto-ordered transition were revealed and discussed. The S(T) dependences were observed to be quite complicated in both temperature ranges. The S(T = 300 K) values are negative for the Ce1-x Sr x MnO3 samples, while for the La1-x Sr x MnO3 ones they are positive for slightly doped samples (at x 0.333). The thermopower results are qualitatively discussed with respect to peculiarities of the conduction process.