Electronic transport and magnetic studies of La1−xCax−0.08Sr0.04Ba0.04MnO3

Lanthanum based mixed valence manganite system La1−xCax−0.08Sr0.04Ba0.04MnO3 (LCSBMO; x=0.15, 0.24 and 0.33) synthesized through the sol–gel route is systematically investigated in this paper. The electronic transport and magnetic susceptibility properties are analyzed and compared, apart from the study of unit cell structure, microstructure and composition. Second order phase transition is observed in all the samples and significant difference is observed between the insulator to metal transition temperature (TMI) and paramagnetic (PM) to ferromagnetic (FM) transition temperature (TC). In contrast to the insulating FM behaviour usually observed in La1−xCaxMnO3 (LCMO) for x=0.15, a clear insulator to metal transition is observed for LCSBMO for the same percentage of lanthanum. The temperature dependent resistivity of polycrystalline pellets, when obeying the well studied law ρ=ρo+ρ2T2 for TTMI. AC magnetic susceptibility study of the polycrystalline powders of the manganite system shows the highest PM to FM transition of 285 K for x=0.33.