Double M-I transitions and low-temperature resistivity minimum of La2/3Ca1/3Mn1−xCoxO3(0⩽x⩽0.15) manganite

A series of Mn-site Co-doping samples La2/3Ca1/3Mn1−xCoxO3 (0⩽x⩽0.15) have been prepared. The structure, magnetic and transport properties of this system have been systematically investigated. All the samples showed good single phase, and the lattice parameters decreased with the increase of doping concentration x. Only one paramagnetic-ferromagnetic transition was observed. The Curie temperature TC decreases gradually and the transition width becomes wider with the increase of x. The abnormal transport properties were induced by Co doping, characterized by the double metal-insulator transitions and low-temperature minimum behavior. The present results are discussed and possible explanations were given based on the related theory and previous reported results.