Transport Properties and Cationic Substitutions in Sr2IrO4

We realized cationic substitutions in Sr₂IrO₄ and measured resistivity, thermoelectric power, and the Hall coefficient. A two-carrier model, reflecting the presence of thermally activated carriers at high temperature, qualitatively explains the behavior of the Hall coefficient of Sr_1.95La_0.05IrO₄ in comparison with Sr₂IrO₄. Concerning the substitution of Ir by different transition metals, Pt with 5d orbitals does not affect the transport properties, contrary to Ti and Rh with 3d and 4d orbitals, respectively. This may be explained by strong spin–orbit coupling involved in Ir and Pt, in comparison with 3d or 4d transition metals.