Research on charge ordering and magnetic properties in La 0.3Ca 0.7Mn 1-xW xO 3 system

Abstract

The perovskite manganite sample La 0.3Ca 0.7Mn 1-xW xO 3 ( x = 0.08, 0.12) was prepared by the solid-state reaction method. The effect of W doping on the Mn site to La 0.3Ca 0.7MnO 3 charge ordering phase and the changing process of magnetic properties were studied through the measurement of the M-T curve, M-H curves, and ESR curves of the sample. The results showed that when x = 0.08, the charge ordering (CO) phase exists in the system, the transition temperature T CO = 275 K, and the system exhibits PM when T > 275 K. The system transforms from spin-disordering paramagnetism to spin-ordering antiferromagnetism in the charge ordering state with the temperature decreasing from 275 K to 230 K. The long-range antiferromagnetism forms and AFM/CO states coexist between 230 K and 5 K. There is a little ferromagnetic component in the AFM/CO background in a low temperature range. When x = 0.12, the CO phase in the system has almost melted completely. There is a little remnant of the CO phase below 150 K. The system exhibits paramagnetism when T > 150 K and transforms from paramagnetism to ferromagnetism when T < 150 K.