Ferromagnetic Curie Temperatures of Iron Solid Solutions with Germanium, Silicon, Molybdenum, and Manganese

Ferromagnetic Curie temperatures of iron‐rich solid solutions with germanium, silicon, molybdenum, and manganese have been determined as a function of solute concentrations. Addition of germanium to iron causes a gradual increase in the Curie temperature, reaching a maximum value of 1046.8 °K at about 1.5 at.% germanium, followed by a gradual decrease. This observation is consistent with the expectations from our previous paramagnetic susceptibility studies. Silicon, molybdenum, and manganese decrease the ferromagnetic Curie point of iron nonlinearly, as a function of solute concentration. The experimental results are briefly compared with the existing theories based on localized moment models. None of them are capable of explaining the observations.