The effect of La3+ substitution on the remanent magnetization, ferromagnetism, and antiferromagnetic charge-ordered phase in Sm0.5Ca0.5MnO3

The influence of La3+ substitution on the remanent magnetization, ferromagnetic (FM) properties, and charge-ordered (CO) antiferromagnetic (AFM) phase of Sm0.5Ca0.5MnO3 is investigated. The particle sizes of LaxSm0.5-xCa0.5MnO3 samples with x = 0, 0.25, 0.375, and 0.5 is estimated to be 2.87, 2.43, 2.57, and 2.09 mu m, respectively, which can be proved by the scanning electron microscope (SEM). The studies on magnetic properties show that the temperature dependence of magnetization M(T) reveal obvious peaks in temperature range of 215-274 K, indicating the appearance of CO-AFM phase. The field-warming (FW) and field-cooling (FC) M(T) curves under applied field of 500 Oe are separated and do not overlap. This thermal hysteresis feature further proves the existence of CO-AFM state. Moreover, the hysteresis loops exhibit the butterfly-like shape, which is also caused by the CO-AFM state in LaxSm0.5-xCa0.5MnO3. With the La3+ substitution, the CO-AFM temperature (TCO-AFM) and the FM-characteristic temperature (T*) decreases, while remanence magnetization (M-r) increases. La3+ ions substitution can suppress the CO-AFM ordering in Sm0.5Ca0.5MnO3, in turn, leading to the decrease of TCO-AFM and T* and the increase of M-r.