In an aspect, a multiphase ferrite comprises a Co2W phase that is optionally doped with Ru; a CFO phase having the formula Mer“Co1−rFe2+zO4, wherein Me” is at least one of Ni, Zn, or Mg, r is 0 to 0.5, and z is −0.5 to 6 0.5; and a CoRu-BaM phase having the formula BaCox+yRuyFe12−(2/3)x−2yO19, wherein x is 0 to 2, y is 0.01 to 2; and the Ba can be partially replaced by at least one of Sr or Ca. In another aspect, a composite can comprise a polymer and the multiphase ferrite. In yet another aspect, a method of making a multiphase ferrite can comprise mixing and grinding a CoRu-BaM phase ferrite and a CFO phase ferrite to form a mixture; and sintering the mixture in an oxygen atmosphere to form the multiphase ferrite.