Layered palladates and their relation to nickelates and cuprates

We explore the layered palladium oxides La₂PdO₄, LaPdO₂, and La₄Pd₃O₈ via ab initio calculations. La₂PdO₄, being low spin d⁸, is quite different from its high spin nickel analog. Hypothetical LaPdO₂, despite its d⁹ configuration, has a paramagnetic electronic structure very different from cuprates. On the other hand, the hypothetical trilayer compound La₄Pd₃O₈ (d8.67) is more promising in that its paramagnetic electronic structure is very similar to that of overdoped cuprates. But even in the d⁹ limit (achieved by partial substitution of La with a 4+ ion), we find that an antiferromagnetic insulating state cannot be stabilized due to the less correlated nature of Pd ions. Therefore, this material, if it could be synthesized, would provide an ideal platform for testing the validity of magnetic theories for high-temperature superconductivity.