XAFS study on Sr2FeMoxW1-xO6 double perovskite series

Sr2FeMoO6 oxide exhibit a half-metallic ferromagnetic (HMFM) ground state and has peculiar magnetic and magnetotransport properties that are very interesting both for applications and for fundamental research in the field of heavily correlated electron systems. In contrast to Sr2FeMoO6, Sr2FeWO6 is an insulator with an antiferromagnetic (AFM) ground state. Doping Sr2FeMoO6 with W, obtaining Sr2FeMoxW1-xO6 compounds, a composition driven metal to insulator transition (MIT) occurs at ~0.25. The nature of such transition is still a matter of debate and different possible scenarios have been proposed. This paper reports a detailed Xray absorption spectroscopy (XAS) study on the Sr2FeMoxW1-xO6 series as a function of composition (0<=x<=1). The results demonstrate the presence of an abrupt change of the local atomic structure at Xc that represents the structural counterpart of the electronic changes associated with the metal insulator transition.