Magnetoresistance in La1−xCaxMnO3 (0≤x<0.4)

The magnetic and transport properties of La1−xCaxMnO3 (0≤x<0.4) have been systematically studied. The magnetoresistance (MR) maximum appears at x=0.2–0.25 and the temperature dependence of MR for x>0.25 shows a much broader profile than that of samples for x=0.2–0.25. Based on a scenario in which there is a short-range charge ordering (CO) state coexisting in the ferromagnetic state matrix for x>0.25, and the least or even no short-range CO state exists in samples for x=0.2–0.25, the above observations can be understood.