Effect of Bi Substitution on Transport and Magnetoresistance Properties of Electron-Doped LaBiCeMnO Ceramics.

Colossal magnetoresistance (CMR) ceramics with starting composition of LaBiCeMnO ( x = 0-0.15) were synthesized using the conventional solid-state synthesis method to investigate the effect of Bi substitution on their magnetic and electrical transport properties. The undoped sample ( x = 0) showed paramagnetic to ferromagnetic (PM-FM) transition at Curie temperature, T = 248 K and metal to insulator (MI) transition at T = 231 K which decreases with Bi content (0 < x < 0.15) indicating weakening of FM phase. At x = 0.15, the susceptibility, χ′ was observed to decrease below 83 K which indicates presence of antiferromagnetic (AFM) clusters in the sample. The decrease in T and T is suggested to be due to the weakening of DE-like interaction involving Mn and Mn as a result of the hybridization between Bi 6 s lone pair with O orbital which increases electron localization. Fitting of the experimental data in the metallic region to scattering models suggested scattering involving electron-electron, electron-magnon, Kondo-like spin-dependant scattering, and electron-phonon interaction. On the other hand, fitting in the insulating region suggests resistivity behavior obeys the adiabatic small polaron hopping (SPH) model. [ABSTRACT FROM AUTHOR]