High temperature topological spin state in a 3d-5d double perovskite oxide Sr₂FeReO₆

Double perovskites composed of 3d and 5d transition metals have attracted significant interest due to predicted to ferrimagnetism above room temperature. These predictions, however, are mostly based on the centrosymmetric bulk crystal structures and neglect spin-orbit coupling which becomes profound due to the 5d transition metals. Here, we report that single phase Sr₂FeReO₆ thin films grown on (110)-oriented DyScO₃ substrates show a sizable topological Hall effect up to 390 K. Structural analysis from second harmonic generation and neutron reflectometry reveal a chiral spin texture that originates from the broken inversion symmetry at the film-substrate interface. These results suggest that epitaxial strain and unquenched spin-orbit coupling cooperatively modify the crystal and electronic structure, introducing competing magnetic exchange interactions to the 3d-5d double perovskite thin film. Our findings highlight the role of interfacial symmetry breaking and spin–orbit coupling in generating emergent chiral spin textures, offering new insights for designing topological magnetic states in complex oxides.