Influence of structural distortions on the Ir magnetism in Ba2−xSrxYIrO6 double perovskites

• Spin–orbit coupling and crystal field splitting compete in IrO6 octahedra.
• Ba2−xSrxYIrO6 presents an opportunity to examine the interplay between SOC and CFS.
• In Ba2−xSrxYIrO6 spin orbit coupling is observed as the dominant effect.

We explore the relative strengths of spin orbit coupling and crystal field splitting in the Ir5+ compounds Ba2−xSrxYIrO6. In the case of strong spin orbit coupling and regular Ir5+ octahedra, one expects a non-magnetic J=0 state; in the case of distorted octahedra where crystal field effects dominate, the t2g manifold splits into a magnetic ground state. We report the results of continuously transitioning from the cubic Ba2YIrO6 double perovskite with ideal octahedra to the monoclinic Sr2YIrO6 double perovskite with distorted octahedra. We see no emergence of an enhanced Ir5+ magnetic moment in the series on increasing the structural distortions, as would have been the case for significant crystal field splitting. The near-constant magnetic moment observed through the Ba2−xSrxYIrO6 series reinforces the notion that spin–orbit coupling is the dominant force in determining the magnetism of iridium-oxygen octahedra in perovskite-like structures.