Effect of high-energy ion irradiation on magnetic properties in Fe–Pt invar alloys

Measurements of AC-susceptibility versus temperature curves were made in thin plates of both ordered and disordered Fe-28.3at.%Pt invar alloys before and after swift heavy ion irradiation. In disordered Fe–Pt invar alloy the Curie temperature decreased about 15 K by the irradiation of 200 MeV Xe-ions to the fluence of 1014 ions/cm2. In ordered Fe–Pt invar alloy the Curie temperature decreased about 128 K to the value just coincide with that of irradiated disordered alloy. By comparing these data to the previous one for Fe–Ni invar alloys, it was concluded that there exist at least two mechanisms having opposite contribution.