Substrate-tuning of correlated spin-orbit oxides

TL;DR

This study explores how substrate-induced strain affects the electronic structures of Sr-iridates, revealing strain-dependent shifts in optical properties and the interplay of magnetic, structural, and spin-orbit factors in their ground states.

Contribution

It provides a systematic ab initio analysis of substrate strain effects on Sr-iridates, highlighting the role of magnetic, structural, and spin-orbit interactions in their electronic properties.

Findings

Tensile strain shifts optical peaks to higher energies.

Electronic correlation and SOC strength are enhanced by tensile strain.

High tunability of hole bands in SrIrO3 near the Fermi level.

Abstract

We have systematically investigated substrate-strain effects on the electronic structures of two representative Sr-iridates, a correlated-insulator Sr$_2$IrO$_4$ and a metal SrIrO$_3$. Optical conductivities obtained by the \emph{ab initio} electronic structure calculations reveal that the tensile strain shifts the optical peak positions to higher energy side with altered intensities, suggesting the enhancement of the electronic correlation and spin-orbit coupling (SOC) strength in Sr-iridates. The response of the electronic structure upon tensile strain is found to be highly correlated with the direction of magnetic moment, the octahedral connectivity, and the SOC strength, which cooperatively determine the robustness of $J_{eff}$=1/2 ground states. Optical responses are analyzed also with microscopic model calculation and compared with corresponding experiments. In the case of SrIrO$_3$, the evolution of the electronic structure near the Fermi level shows high tunability of hole bands, as suggested by previous experiments.