Giant Magnetoresistance in the Half-Metallic Double-Perovskite Ferrimagnet Mn2FeReO6

The first transition‐metal‐only double perovskite compound, Mn2+2Fe3+Re5+O6, with 17 unpaired d electrons displays ferrimagnetic ordering up to 520 K and a giant positive magnetoresistance of up to 220 % at 5 K and 8 T. These properties result from the ferrimagnetically coupled Fe and Re sublattice and are affected by a two‐to‐one magnetic‐structure transition of the Mn sublattice when a magnetic field is applied. Theoretical calculations indicate that the half‐metallic state can be mainly attributed to the spin polarization of the Fe and Re sites. The first transition‐metal‐only double perovskite, Mn2+2Fe3+Re5+O6, displays ferrimagnetic ordering up to 520 K and a giant positive magnetoresistance of up to 220 % at 5 K and 8 T. These properties result from the ferrimagnetically coupled Fe and Re sublattice and are affected by a two‐to‐one magnetic‐structure transition of the Mn sublattice when a magnetic field is applied.