Abstract: La_0.7Ca_0.3Mn_1-xCu_xO₃（ bulk samples with different Cu contents (x=0~0.15) were prepared by solid reaction method. Temperature dependence of Cu doped samples was studied in a range of 77~300 K. The result indicates that the resistivity of the sample without Cu doped follows the T^2.5 model in ferromagnetic phase at low temperatures, while in paramagnetic phase it obeys the small polaron hopping model. Low doped sample match the T^4.5 model at low temperatures in ferromagnetic phase. With the doping content increasing, no single model satisfies our experiment in both ferromagnetic phase and paramagnetic phase. This indicates much more complicated electric transport mechanism of high doped samples.

Key words: La_0.7Ca_0.3Mn_1-xCu_xO₃（, peroveskite, electric transport, polaron