Structure and magnetic properties of substitution of K for La in LaMnO3 perovskite

A serial single phase of lanthanum manganites with potassium-doped was successfully synthesized and can be indexed in rhombohedral system with space group R3¯c. Structural, magnetic and magnetoresistance properties of LaMnO3 with K-doped have been investigated systematically. Magnetic and electrical measurements showed that the samples display change from ferromagnetic to paramagnetic transition and from metal to insulator properties with increasing temperatures, respectively. Thermal magnetic curves of La1−xKxMnO3 samples show two characteristic temperatures. The one located at low temperature is charge-ordering temperature, which is almost independence of metal-insulator transition temperature, TMI, and the other is magnetic transition temperature (TC), which is linearly correlated with TMI. The magnetoresistance effect decreases with temperature increasing except La0.35K0.65MnO3 which exhibits increase, then, lower following increase with enhancing temperatures.