Superconductivity and Spin Fluctuations in the<i>Ir</i>-Ni,<i>Ir</i>-Co, and<i>Ir</i>-Fe Alloy Systems

Abstract

The superconducting transition temperatures of Ir-Ni, Ir-Co, and Ir-Fe alloys have been measured in the temperature interval 0.10-0.040 \ifmmode^\circ\else\textdegree\fi{}K. It is shown that the rates of change of $\mathrm{ln}{T}_{c}$ with impurity concentration for these systems provide quantitative evidence that localized spin fluctuations are responsible for the suppression of superconductivity when these rates are compared with the rates of increase of the specific-heat coefficient $\ensuremath{\gamma}$ and the susceptibility $\ensuremath{\chi}$.