Thermoelectronic properties of the strongly-correlated oxide BaIrO3

We synthesized polycrystalline samples of Ba_1-xSr_x IrO₃ (0 les x les 0.2) using a solid-state reaction method, and measured their magnetization, resistivity and thermopower. The thermopower of BaIrO₃ slightly increases with decreasing temperature above T_C, and is suddenly enhanced below T_C = 180 K due to the pseudogap in the density of states. At 75 K, it reaches a maximum value of 230 muV/K. With increasing Sr concentration, the thermopower systematically decreases, accompanied by a slight decrease of T_C. For x = 0.2, the maximum value of the thermopower and T_C are 50 muV/K and 173 K, respectively. These results indicate that the gap is suppressed by chemical pressure due to the substitution of Sr for Ba