Effect of Silver Substitution on Electrical Transport and Magnetoresistance of La0.8Ca0.2MnO3

In this work, we have investigated the effect of silver substitution on electrical transport behavior and magnetoresistance of La0.8-xAgxCa0.2MnO3 (x = 0 and 0.05). Preparation and study of structural and microstructure of both samples have been reported on previous work. Temperature-dependent resistivity has been measured at temperature range of 15-285 K with zero field cooling. Magnetoresistance effect has been measured at 15, 100, and 285 K with magnetic field up to 1 T. The electrical transport behavior of both samples are quite well described by a theory based on the Percolation model. The electrical conduction mechanism at low temperature can be explained by a theory based on Kondo-like spin-dependent scattering, electron-electron, electron-magnon, and electron-phonon scattering. It was found that silver substitution increases the metal-insulator transition temperature (TM-I) from 197.55 to 277.56 K, and Curie temperature (T-c(Mod)) from 217.25 to 278.65 K. Moreover, the maximum magnetoresistance value of both samples was obtained at 15 K.