AMORPHOUS AND QUASI-CRYSTALLINE ALMN AND ALFE PHASE SYNTHESIS BY ION-BEAM MIXING AND RELATED TRANSPORT-PROPERTIES

AlMn and AlFe multilayers have been mixed at various temperatures (450 , 493 and 77 K) with 800 keV Xe+ ions. The mixing stages as a function of dose at various temperatures and the nature of the synthesized pha ses have been characterized using three complementary techniques: Ruth erford backscattering spectrometry (RBS) to observe the spatial distri bution resulting from the mixing process at the interfaces; transmissi on electron microscopy (TEM) observations to determine the microstruct ures and phases; and conversion electron Mossbauer spectroscopy (CEMS) in the case of AlFe alloys for the study of local order evolutions. M ixing efficiency and nature of the elaborated phases depend on ion dos e and temperature of the sample. A dose of about 3 x 10(16) ions/cm2 i s necessary to obtain homogeneous amorphous alloys at 77 K, while the quasicrystalline phases are formed at 450 K (AlMn) or 493 K (AlFe) for a dose of 8 x 10(15) ions/cm2. In the AlFe alloys, the local environm ents of the Fe-atoms deduced from CEMS show different characteristic e volutions for amorphous and quasicrystalline phases with a combination of several sites the relative proportions of which vary at each inter mediate mixing stage. Optical (reflectivity) and transport (resistivit y, magnetoresistance) measurements performed on the homogeneous mixed films exhibit different electronic structures of the phases and differ ent magnetic behaviors for AlMn (spin glass transition) and AlFe (weak localization).