Characterization of magnetic property of double-perovskite (Sr2−xGdx)FeMoO6

Structural and magnetic properties of rare-earth doped (Sr2−xGdx)FeMoO6 compounds (x = 0, 0.05, 0.1, 0.13 and 0.15) have been investigated. All the compounds are of single phase and belong to the space group I4/m. Because of the small size of Gd3+ ion (compared to that of Sr2+ ion), obvious structural distortion is introduced in the compounds and imposes an important influence on the magnetic property of (Sr2−xGdx)FeMoO6. The competing interaction between structural distortion and electron injection results in a non-monotonic evolution of the Curie temperature (TC): TC decreases firstly and then increases, with a minimum value at x ≈ 0.07. Contrary to the magnetic behavior of Eu3+ ion in (SrEu)FeMoO6 compound, the long-range ordered Gd3+ moment is parallel to that of Fe3+ ion at low temperature, and the contribution of the dopant to the saturation magnetization of (Sr2−xGdx)FeMoO6 is 6.75-7.15 μB per Gd3+ ion, which is comparable to the magnetic moment of a free Gd3+ ion (7.0 μB). Above results indicate that although the rare earth elements exhibit similar chemical and optical character, their magnetic behavior in Sr2FeMoO6 compound differs to a large degree.