Research: Correlation induced electron-hole asymmetry in quasi- two-dimensional iridates

The iridate Sr₂IrO₄ closely resembles the cuprate La₂CuO₄ from a magnetic and crystallographic point of view. When doped with charge carriers, the insulating, antiferromagnetic cuprate La₂CuO₄ becomes a superconductor with a relatively high transition temperature. This raises the question how far Sr₂IrO₄ is away from superconductivity upon doping. The rst step towards understanding this issue is provided by a study of the motion of a single charge carrier that is introduced to the compound. Our theoretical study shows that an electron added to Sr₂IrO₄ forms a spin-polaron, similar to the cuprates. But the situation of a removed electron - an added hole - is far more intricate. In this case complex many-body con gurations of singlet and triplet character form. This effect is due to the presence of strong spin-orbit coupling in iridium ions in combination with electronic correlation effects. As a consequence the calculated photoemission spectrum of Sr₂IrO₄ (panel) is very different from its inverse photoemission spectrum. We conclude that, unlike in the case of the cuprates, the electronic structure of electron and hole doped iridates are fundamentally different.

E. M. Pärschke, K. Wohlfeld, K. Foyevtsova, J. van den Brink,
Correlation induced electron-hole asymmetry in quasi- two-dimensional iridates
Nat. Commun. 8: 686 (2017)