The magnetic properties of the Invar alloy Fe64Ni36 have been investigated
by x-ray emission spectroscopy as a function of pressure up to 20 GPa. With
increasing pressure, the amplitude of the Fe local moment, deduced from th
e Fe K beta line satellite intensity, is reduced at two characteristic step
values. This pressure dependence is interpreted in terms of transitions fr
om a high-spin state to a low-spin state at approximate to5 GPa followed by
a transition to a nonmagnetic state above 15 GPa. This behavior provides a
microscopic picture of the Fe magnetism in agreement with the 2 gamma -sta
te model.