Mössbauer and Resistivity Study of Dilute Sn-Transition Metal Alloys

We have measured the hyperfine field of Sn119 nuclei as a function of temperature in dilute (¼ at.%) alloy of Sn in Fe and Ni from 4.2°K to the Curie temperature. For Fe, the reduced field vs reduced temperature curve decreases more rapidly than the corresponding reduced magnetization curve. If one assumes s electron screening of the Sn atom, and that the Sn nuclei respond to a reduced magnetization predicted for nearest neighbors of a nonmagnetic impurity atom by the molecular field model of Lovesey and Marshall, the results can be partially explained as arising from a decrease in the strength of the Ruderman-Kittel interaction due to the decrease of the electronic mean free path at elevated temperatures. For Ni, the reduced field also decreases more rapidly than the reduced magnetization and agrees reasonably well with a curve obtained by applying the above mentioned Lovesey-Marshall corrections to the reduced magnetization of Ni. The results are consistent with the concept of Sn impurity screening by d electrons. Preliminary results for a dilute hcp Co–Sn alloy up to T/Tc = 0.47 show a much larger, more anomalous decrease of field with temperature, which might be associated with the formation of a localized moment at the Sn site. Additionally, measurements of the residual resistivity in the three alloys and of resistivity vs temperature for the Fe–Sn and Ni–Sn systems have been made and a discussion of the results is given.