Localized Moment of Dilute Fe in Iridium

Abstract

The Mössbauer effect of 57Fe impurities in various host metals has proved to be a useful tool in determining any localized moment on the impurity. In general the results have been in good agreement with those obtained from susceptibility measurements for higher Fe concentrations. We report measurements on very dilute Fe in Ir taken over the range 1.1° to 300°K and 0 to 62 kOe applied field. These measurements yield s(J+1)/J=66±10°K and μ Hsat(J+1)/J=−188±30 μB−kOe, where J is the spin associated with the localized moment μ, Hsat is the internal field for fully aligned spins, and s is an interacting host field which tends to depolarize the spins being aligned in the external field. The quality of the fit does not allow an independent determination of μ; however, it certainly is not zero. Similar results were obtained for an Ir999Fe1 alloy. This is in contrast to recent susceptibility measurements where for this alloy no localized moment was found; susceptibility measurements on an Ir99Fe1 alloy indicate the presence of a localized moment.