Establishment and melting of charge ordering in La0.3Ca0.7Mn1-xWxO3 system

Polycrystalline samples of La0.3Ca0.7Mn1-xWxO3 (0.00 <= x <= 0.15) were prepared by conventional solid-state reaction method. The influence of W doping at Mn site on the magnetic transition of La0.3Ca0.7Mn1-xWxO3 system was studied by the measurements of magnetization-temperature (M-T) curves, magnetization-magnetic intensity (M-H) curves, and ESR spectra. The results show that, with the increase in W doping amount, the magnetic transition of the system exhibits a complicated charge process, when the doping amount is 0.00 <= x <= 0.08, the charge-ordering(CO) phase exists in the system, AFM/CO states coexist below the transition temperature, and the charge-ordering temperature(T-infinity) goes up with the increase in W doping content; when x >= 0.12, the charge ordering (CO) state of the system weakens and melts, and paramagnetism-ferromagnetism (PM-FM) transition exists at extremely low temperature.