The electronic structure of epitaxially strained iridate thin films and superlattices from first principles

Within the Ruddlesden-Popper iridates Sr$_{n+1}$Ir$_n$O$_{3n+1}$, strong spin-orbit interactions lead to the formation of a half-filled, narrow $J_\textrm{eff}=1/2$ band and filled $J_\textrm{eff}=3/2$ bands. This places the iridates in the vicinity of a Mott transition, which is sensitive to perturbations in crystal structure, despite relatively weak on-site Coulomb interactions [1]. For example, Sr$_2$IrO$_4$ ($n=1$) is an antiferromagnetic Mott insulator that displays an almost rigid coupling between spin canting and IrO$_6$ octahedron rotations [2], while epitaxially stabilized SrIrO$_3$ ($n=\infty$) is a correlated metal. In this talk, we will discuss from first-principles within the LDA+SO+$U$ approach the possibility to engineer the electronic structure of SrIrO$_3$ and CaIrO$_3$ thin films using epitaxial strain and by creating superlattices of the form ($A$IrO$_3$)$_m$($A'B$O$_3$)$_{m'}$ with $A$, $A'$ = Ca, Sr. [1] S.J. Moon, H. Jin, K.W. Kim, W.S. Choi, Y.S. Lee, J. Yu, G. Cao, A. Sumi, H. Funakubo, C. Bernhard, and T.W. Noh, PRL 101, 226402 (2008). [2] B.J. Kim, H. Jin, S.J. Moon, J.-Y. Kim, B.-G. Park, C.S. Leem, J. Yu, T.W. Noh, C. Kim, S.-J. Oh, J.-H. Park, V. Durairaj, G. Cao, and E. Rotenberg, PRL 101, 076402 (2008).