Electronic transport and magnetoresistivity of La0.4Bi0.1Ca0.5−xSrxMnO3 (x = 0.1 and 0.2)

Electrical resistivity and magnetoresistive behaviour of bismuth-substituted lanthanum manganites La0.4Bi0.1Ca0.5−xSrxMnO3 (x = 0.1 and 0.2) were systematically studied by varying the temperature from 2 to 300 K and the magnetic field up to 12 T. The samples were found to crystallize in rhombohedral structure and their morphology shows near-spherical nanosize crystallites. Charge ordering was observed in both the samples under zero field conditions and corresponding transition temperature TCO was found to decrease with the increase of x. Resistivity measurements with magnetic field also showed suppression of magnetoresistivity (MR) with the increase of x and the maximum MR was found to be 98 and 93% for x = 0.1 and 0.2, respectively, at 10 T. In the high-temperature domain, the electronic transport was observed to be dominated by the variable range hopping mechanism for both the samples, whereas in the low-temperature domain the electrical conduction of x = 0.1 sample was observed to be contributed by various other electron scattering mechanisms.