No abstract

The magnetic properties of FeGa2O4, FeAl2O4 and FeIn2S4 have been studied by neutron diffraction, how fdield susceptibility and Mössbauer measurements. A strong spin-glass character is observed for the sulfide compound while less pronounced for the oxide compounds

Mössbauer studies of cobalt- and nickel-doped BaFe(2)As(2) show that the s-electron density at the (57)Fe nuclei, as measured by the isomer shift, is the same as that for the parent BaFe(2)As(2). Apparently, the electron population of the d shell, which shields the s-electron density at the nuclei, remains unchanged. We invoke the involvement of p-orbital hybridization with the d orbital in Fe-As bonding. Furthermore, the shrinkage of the lattice on substitution enhances the As-As sp hybridization, providing a path for the migration of additional electrons. The proposed mechanism is consistent with Hall coefficient and thermoelectric effect measurements.