The effect of La³⁺ substitution on the remanent magnetization, ferromagnetism, and antiferromagnetic charge-ordered phase in Sm_0.5Ca_0.5MnO₃

Abstract

The influence of La³⁺ substitution on the remanent magnetization, ferromagnetic (FM) properties, and charge-ordered (CO) antiferromagnetic (AFM) phase of Sm_0.5Ca_0.5MnO₃ is investigated. The particle sizes of La_xSm_0.5-xCa_0.5MnO₃ samples with x = 0, 0.25, 0.375, and 0.5 is estimated to be 2.87, 2.43, 2.57, and 2.09 μm, 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 La_xSm_0.5-xCa_0.5MnO₃. With the La³⁺ substitution, the CO-AFM temperature (T_CO-AFM) and the FM-characteristic temperature (T*) decreases, while remanence magnetization (M_r) increases. La³⁺ ions substitution can suppress the CO-AFM ordering in Sm_0.5Ca_0.5MnO₃, in turn, leading to the decrease of T_CO-AFM and T* and the increase of M_r.