ANNEALING EFFECTS ON THE STRUCTURE AND MAGNETIC-PROPERTIES OF NI TI MULTILAYERS/

Interfaces of Ni-Ti multilayers deposited by dc triode sputtering unde r high purity conditions (base pressure 10(-7) Torr plus getter-sputte ring) and their thermal evolution are studied. This was achieved by co mbining high energy electron diffraction, secondary ion mass spectrome try and magnetometry. The study shows the existence of a non-magnetic interfacial amorphous layer due to interdiffusion over very short dist ances during deposition. A marked asymmetry between the two sides of a given layer is observed, due to interfacial contamination of Ti by C and O acting as a diffusion barrier. Annealing treatments yield an inc rease in amorphization and finally crystallization of the interfacial amorphous phase to a NiTi stable phase.