Magnetic, electric and thermoelectric properties of the quasi-1D cobalt oxides Ba_1-xLa_xCoO₃ (x = 0, 0.2)

The quasi-1D structure-type ferromagnetic (FM) cobalt oxide BaCoO₃ was doped with La to a composition Ba_0.8La_0.2CoO₃ (hexagonal, a = 5.585(1) angstroms and c = 4.721(1) angstroms), introducing 0.2 electrons per formula unit. Magnetic, electric and thermoelectric properties are compared to those of BaCoO₃. The electrical resistivity decreases approximately one order of magnitude at room temperature (5×10^-1 Ω cm), but remains semiconducting. The nearest-neighbor magnetic interaction in chain is FM (J/k_B to approximately +94 K), and no manifest magnetic long-range order was observed above 5 K. Variable-range hopping behavior in the thermopower was found. Anderson localization is most likely to explain the poor electrical conductivity, as was suggested for the parent material BaCoO₃.