The formation of orbital moments on iron impurities

Using the high specificity and sensitivity of the in-beam perturbed γ-ray angular distribution method, we have investigated the magnetic behavior of very dilute 54 Fe probes in Ag1−xAux alloys. The nuclear damping time and local susceptibility of Fe are found to depend strongly on its local environment, showing inhomogeneous line broadening as well as discrete magnetic responses due to the different configurations of Ag/Au nearest neighbors. The results can be understood with the aid of ab initio calculations of electronic structure, magnetic moments and hyperfine fields. They underline the central importance of orbital magnetism for understanding the experimental results.