Low temperature resistivity anomalies in bismuth doped manganites

With a view to understand the low temperature resistivity behaviour, especially below their metal insulator transition temperature, a series of bismuth doped lanthanum strontium manganites with compositional formula, La0.67−xBixSr0.33MnO3 (where x = 0, 0.1, 0.2, 0.3) were prepared by the sol–gel method. After characterizing these materials, a systematic investigation of electrical resistivity both as a function of temperature and magnetic field was undertaken. It has been found that the electrical resistivity of all the samples exhibits an upturn at about 30 K in the ferromagnetic region (T < TC). The anomalous behaviour of electrical resistivity in the low temperature region was explained by a theory based on Kondo-like spin dependant scattering, electron–electron, electron–phonon and electron–magnon scattering. The high temperature electrical resistivity behaviour (T > TP) was explained using adiabatic small polaron model.