Transport and magnetic properties of Sr doped Nd0.55Ca0.45MnO3

The effect of Sr doping on the transport and magnetism properties of charge/orbital-ordered Nd0.55Ca0.45MnO3 is investigated. A low temperature phase transition from a charge/orbital ordered insulator to a ferromagnetic metal was founded in the Nd0.55(Ca1−xSrx)0.45MnO3 samples. The ground state is the charge/orbital ordered insulator at x 0.3 it changes to a ferromagnetic metal. The resistivities of the samples exhibit almost ideal percolation behavior with a percolation threshold of 0.3. Therefore, this system shows an intricate competition between metallic ferromagnetism and charge/orbital ordered insulator and the percolation behavior demonstrates that the relative volumes of ferromagnetic phase and charge/orbital phases changes with the doping content x and temperature.