Insight on the electronic state of Sr2IrO4 revealed by cationic substitutions

We report the electrical resistivity, thermoelectric power and magnetization of Sr2-xLaxIrO4 (x = 0 and 0.05) and Sr2Ir1-yRhyO4 (y = 0.05, 0.1 and 0.2) measured below room temperature. In Sr2IrO4, electrons (La substitution) or holes (Rh substitution) can be doped, which lead to a strong decrease of the resistivity. In particular, a nearly-metallic state is realized in the case of Rh doping. The thermoelectric power turns out to be metallic-like for y = 0.2. The presence of a gap in the electronic band structure is robust against these substitutions. From various experimental data, similarities with the 3D charge density wave compound, BaBiO3, are suggested. Nevertheless, rather than a charge density wave, our scenario implies the presence of a spin density wave