Nature of "Disorder'' in the Ordered Double Perovskite Sr2FeMoO6

Abstract

The degree of B/B' alternate cation order is known to heavily influencethe magnetic properties of A(2)BB'O-6 double perovskites although thenature of such disorder has never been critically studied. Our detailedx-ray absorption fine structure studies in conjunction with synchrotronradiation x-ray diffraction experiments on polycrystalline Sr2FeMoO6samples with various degrees of disorder reveal that a very high degreeof short range order is preserved even in samples with highly reducedlong range chemical order. Based on these experimental results and withthe help of detailed structural simulations, we are able to model thenature of the disorder in this important class of materials and discussthe consequent implications on its physical properties.