Effect of GeV-ion irradiation on magnetic properties of Fe-Ni invar alloys

Abstract High-energy ion irradiation was performed using a ring-cyclotron installed at the Institute of Physical and Chemical Research (RIKEN). The incident ions were Ta with the energy of 3.71 GeV, and the fluence was fixed to 5 × 10 12 ions/cm 2 . As a target, three sheets of square plates of Fe–30.2 at.% Ni invar alloys were put one upon another. The shift of the Curie temperature T C of the first sample was 14 K, while that of the second one was 22 K. Comparing these two, the shift was as large as 46 K in the last sample in which ions stopped in the middle. It was concluded that there are at least two different mechanisms that contribute to the shift of T C .