Study on the anomalous thermopower and resistivity of (Bi, Pb)–Sr–Co–O: Evidence of a narrow band contribution with Anderson localization

The resistivity and thermopower of the misfit-layered (Bi, Pb)–Sr–Co–O system with different Pb concentration were investigated. The thermopower is surprisingly large and T-independent with metallic resistivity at high temperatures, suggesting a narrow band contribution. The resistivity starts to increase below about 90 K, while no change can be seen in the thermopower, which is evidence of Anderson localization in a disordered structure.