PHASE-TRANSITIONS, CRYSTALLOGRAPHIC AND LOCAL MAGNETIC-ORDERING OF FE3PT

A sharp drop in saturation magnetization is known to occur within a na rrow range of the Fe-Pt alloy composition of nearly 25 at.% Pt. So far the nature of this phenomenon has not been entirely clarified. Fe3Pt alloy different thermal treatment was studied by X-ray diffraction and Mossbauer spectroscopy at room temperature. Owing to different therma l treatments of the alloy having initially a bcc structure, its fee mo dification is obtained either in an ordered or disordered state. It is shown that the disordered fee structure could be in two spin (ferroma gnetic and paramagnetic) states whereas the ordered structure has only a ferromagnetic state. The availability of the paramagnetic state in the disordered structure suggests an explanation of the above phenomen on.