Comparing study of magnetic-ion and nonmagnetic-ion doping effect at Mn site in La0.825Sr0.175MnO3 compound



Structural, magnetic, and transport properties of La0.825Sr0.175MnO3 samples doped with magnetic (Fe3+, Cr3+) and nonmagnetic (Ga3+, Al3+) ions have been studied comparatively. The structure does not change by nonmagnetic ion doping, whereas magnetic ion substitution can change the structure of the system significantly. All the doped samples show a lower Curie temperature as compared to that of the undoped sample. The change of Curie temperature TC for the magnetic-ion-doped samples is quite larger than that of the nonmagnetic-ion-doped samples. The electron configuration is suggested to play an important role in determining the change of TC for the magnetic-ion-doped samples, whereas the decrease of TC in nonmagnetic-doped samples is considered to originate mainly from the variation of local lattice. The Fe-doped sample shows semiconducting transport behavior in the whole studied temperature range besides a kink near TC. Except for two obvious M–I transitions, another inflexion-like anomaly in the ρ(T) curve at low temperatures is observed for the Ga-, Cr-, and Al-doped samples and the inflexion is suggested to be related to a two transport channel model in these samples.