Electronic and Magnetic Structures ofSr2FeMoO6

We have investigated the electronic and magnetic structures of ${\mathrm{Sr}}_2{\mathrm{FeMoO}}_6$ employing site-specific direct probes, namely x-ray absorption spectroscopy with linearly and circularly polarized photons. In contrast to some previous suggestions, the results clearly establish that Fe is in the formal trivalent state in this compound. With the help of circularly polarized light, it is unambiguously shown that the moment at the Mo sites is below the limit of detection $(<0.25\mathrm{}{\mu }_B)$, resolving a previous controversy. We also show that the decrease of the observed moment in magnetization measurements from the theoretically expected value is driven by the presence of mis-site disorder between Fe and Mo sites.