Xe ions irradiation on bcc-Fe/Tb multilayers

Two bcc-Fe/Tb MLs with tFe far from and close to the limit of crystallization of Fe layers were irradiated with Xe ions at various fluences and investigated by 57Fe Moessbauer spectrometry at 300 K. Two structural effects were evidenced: the usual mixing of layers and a demixing of the Fe and Tb atoms at the interfaces. The first process, observed in the two samples, destroys progressively the layered structure and leads to the formation of the corresponding amorphous alloy at high fluence. The second process, observed only at low fluence before the step of mixing for the multilayer close to the limit of crystallization of Fe layers, features the thermal metastability of this multilayer which relaxes towards a minimal energy state. It increases the pure iron part in the center of the iron layers, thus sharpening the interfaces. (orig.)