Disorder-Induced Griffiths-like Phase and Charge Localization in Sr ₂ FeRuO ₆

A comprehensive understanding of complex transition-metal oxides is key to designing next-generation spintronic materials with tailored magnetic and transport functionalities. We investigate the interplay among structural disorder, frustrated magnetism, and localized charge transport in the 3d–4d hybrid double perovskite Sr2FeRuO6. The compound adopts a monoclinic structure with significant B-site antisite disorder that drives its unconventional behavior. Magnetic measurements uncover a robust Griffiths phase extending well above the ordering temperature, evidencing stable short-range ferromagnetic clusters within a disordered matrix. Electrical transport remains strongly localized, transitioning from small-polaron hopping at high temperatures to variable-range hopping at intermediate temperatures. These results position Sr2FeRuO6 as a representative 3d–4d hybrid system in which quenched disorder stabilizes spin inhomogeneity, while polaronic and hopping transport are also observed.