Anomalous spin state of Fe in double perovskite oxide Sr2FeWO6

In the series of Sr2FeTO6 (T = 4d or 5d, the valence of Fe is 3 + in most o f the compounds. However, recently we have found that the Sr2FeWO6 has Fe2 state. Sr2FeWO6 is an insulator with an antiferromagnetic transition tempe rature of 37 K. From the Mossbauer experiment, below similar to 20 K, a cen ter shift of + 1.2 mm/s relative to metallic iron and a quadrupole splittin g of 1.9 mm/s are obtained. The quadrupole splitting has strong temperature dependence. The hyperfine field is similar to 110 kOe which seems to be qu ite small. We concluded that the iron ground state of Sr2FeWO6 is Fe2+ high -spin (S = 2) state. (C) 2000 Elsevier Science B.V. All rights reserved.