Modification of the structure and the physical properties of Fe/Si multilayered films by ion-beam mixing

The influence of ion-beam mixing (IBM) on the structure, magnetic, magneto-optical, and optical properties of Fe/Si multilayered films (MLF's) is investigated. Mixing was performed with Ar+ ions of an energy of 80 keV and a dose of 1.5x10(16) Ar+/cm(2). It is shown that IBM destroys the layered structure of the MLF down to a depth of about 110-150 nm, and leads to the formation of a phase which is characterized to have a perfect crystalline structure, a low coercivity, and a Curie temperature of about 550 K. It is suggested that the phase formed by the IBM is a metastable Fe2Si silicide with a B2 type of structure. Annealing of the ion-beam mixed Fe/Si MLF at 720 K further destroys the undisturbed layered structure at the bottom, and also leads to a decomposition of the Fe2Si phase into a metastable magnetically hard Fe5Si3 silicide and, presumably, Fe3Si.