Effect of disorder on transport and electronic structure in LaCo1−xNixO3 system

We have systematically investigated magnetization, resistivity, thermopower and X-ray photoemission spectra(XPS) in LaCo1−xNixO3 ( 0 ∼ x ∼ 0.5 ) system. It is found that the transport mechanism is variable range hopping(VRH) for x ≤ 0.1 , and thermally activated hopping for 0.2 ≤ x ≤ 0.4 . While the transport mechanism is far from the hopping process for x ≥ 0.4 , invalidity of the hopping process for x = 0.4 and metallic behaviour for x = 0.5 , indicates that the MIT is around x = 0.4 . For samples ( x ≥ 0.2 ), the thermopower can be explained well by Cutler–Mott formula which is suitable for metal with strong disorder. The metal-insulator transition in this system is a Mott–Anderson transition in which disorder effects dominates the MIT, in the presence of electron-electron correlations. The results indicate a two-band behaviour in LaCo1−xNixO3. We propose possible evolution of electronic structure to explain these phenomena.