Ion beam mixing of some amorphous magnetic films

Ion beam mixing is investigated as an alternate preparation technique for obtaining an amorphous magnetic thin films. We studied the structural and magnetic properties of (Fe20Ni80)1-xSix, CO1-xNbxand GdxFe1-xthin films. The samples were prepared by depositing the two constituants sequentially under ultra high vacuum and were irradiated by Xe ions at an energy of 200 to 400 keV and doses of 3 to 6×10¹⁵ion/cm². Composition and structural properties were determined by R.B.S., RHEED, TEM and SIMS. F.M.R. measurements showed that in accordance with structural investigations only a 500 Å thick surface layer is mixed at 200 keV, but for 400 keV one obtains a magnetically uniform sample. Increasing the dose permits to improve the short range chemical order. Low temperature measurements confirmed the good quality of the samples mixed at 400 keV, where Msfollows a Blochs law as a function of temperature. The variations of the coercive field, the induced anisotropy as a function of mixing parameters and for the various alloys is also reported. In Gd-Fe samples the mixing is far from complete showing that the efficiency of the mixing depends upon the nature of the alloy.