Charge ordering and magnetic properties of LaxSm0.5-xCa0.5MnO3 manganite

In this paper, the effect of La 3+ doping on the structure, charge ordering and magnetic properties of Sm 0.5 Ca 0.5 MnO 3 manganite has been studied. A series of La x Sm 0.5-x Ca 0.5 MnO 3 ( x = 0, 0.25, 0.375, 0.5) samples are prepared by traditional solid state reaction. The crystal structures are studied by X-ray diffraction technology. The results show that they are single-phase and orthorhombic structures. The change of La 3+ ion concentration does not change the crystal structure of the samples. The surface morphology and particle size of the samples are studied by scanning electron microscope. The average particle size of the samples is several micrometers. Energy-dispersive spectrometer is used to detect the composition of the samples. The results show that the actual element composition of the samples is consistent with that of the modulated element. Magnetic properties are analyzed by magnetization versus temperature (M–T) curves and magnetic hysteresis (M-H) loops. Below 50 K, the zero-field-cooling (ZFC) and field-cooling (FC) M–T curves diverge obviously, which is a typical feature of spin glass transition. The ZFC and FC M–T curves show a significant protuberance peak between 215 and 274 K, which represents the existence of charge-ordered (CO) anti-ferromagnetic (AFM) state. With increasing La 3+ ion doping concentration, the CO temperature gradually decreases. Moreover, the butterfly-type M-H loops also confirm the existence of CO-AFM phase in samples. In a few words, the competition between FM and AFM phases determines the charge ordering behavior and magnetic properties of the samples.