X-ray photoemission study ofSr2FeMoO6andSrMoO4films e

An investigation of the Fe and Mo oxidation states in Sr2Fe2−xMoxO6 (0.25⩽x⩽1.0) double perovskites by X-ray absorption spectroscopy

“…Although no definitive values have been reported, the oxidation state of Fe is generally found to be between 2+ and 3+ while the oxidation state of Mo is found to be between 5+ and 6+ [15,21,18,[31][32][33][34][35]. This disagreement probably arises from the complex nature of Sr 2 FeMoO 6 , with the material being sensitive to a wide variety of variables.…”

“…For example, these materials are ferrimagnetic, with a Curie temperature reported to be between 410 and 450 K [9]. Here, ferrimagnetism arises from a double exchange mechanism, which results from the ferromagnetic alignment of Fe 3d electrons and the antiferromagnetic alignment of Mo 4d electrons [15,18,19]. This model assumes Fe adopts a 3+ oxidation state and Mo adopts a 5+ oxidation state, and the theoretical maximum saturation magnetization is 4 l B , though experimentally, the saturation magnetization has always been observed to be less [20][21][22].…”

MoxCu1−xSr2YCu2Oy (0.3≤x≤1) revisited: Superconductivity, magnetism and the molybdenum oxidation state

“…Fitting of the XPS spectra of Mo 3d core levels allows us to confirm the large content of Mo 5 þ . The presence of Mo 5 þ and Mo 6 þ is identified by the energy shifts of their core levels assigning the doublet at 232 eV and 235.1 eV (3d 5/2 and 3d 3/2 ) to Mo 5 þ and the one's at 233.3 eV and 236.4 eV (3d 5/2 and 3d 3/2 ) to Mo 6 þ as proposed [19]. Annealing under oxygen atmosphere is enhancing the Mo 6 þ state.…”

Effects of the defects on the structural, electronic and magnetic properties of Sr2FeMoO6

“…The magnetic structure is an ordered arrangement of parallel Fe 3þ (3d 5 , S ¼ 5/2) magnetic moments antiferromagnetically coupled with Mo 5þ (4d 1 , S ¼ 1/2) moments, resulting in a net magnetic moment of 4 m B /formula unit (f.u.) at low temperatures [4].…”