Onset of magnetic order in the giant moment system PdCo

The measured AC susceptibility of PdCo alloys with 3 to 7.5 at.% Co at 5 kHz in applied fields of 0-250 Oe is typical of a bulk ferromagnet near its ordering temperature. The principal maximum in the susceptibility shifts to lower temperatures relative to the zero field maximum as the applied field is increased. Concurrently a second, narrower peak appears which has a small upward shift in temperature, and is identified as the true critical susceptibility maximum.