Unveiling the ambient-condition structure of Sr2FeIrO6: a triclinic phase through synchrotron-based X-ray techniques and high pressure.

Double perovskites with the formula A2BB'O6, such as Sr2FeIrO6, are being explored as unique platforms for unveiling diverse structural, electronic and magnetic properties. Inclusion of 3d and 5d transition metals in the B and B' sites, as in Sr2FeIrO6, enables the study of electron correlation and spin-orbit coupling effects to tailor promising properties. The structure of Sr2FeIrO6 under ambient conditions has been widely debated, with theoretical and experimental studies suggesting several potential structures. This uncertainty complicates the understanding of its magnetic and electronic behaviours. High-pressure X-ray diffraction measurements, complemented by high-resolution powder X-ray diffraction studies under ambient conditions, have provided a definitive structural characterization of Sr2FeIrO6, crucial for interpreting its properties and guiding future research.