VERY THIN FE NI MODULATION MULTILAYER FILMS UNDER ION-BOMBARDMENT/

We investigated the effect of noble gas irradiation (He, Ne, and Xe) o n Fe-Ni multilayers with a very thin modulation and nominal compositio n in the Invar region Fe0.63Ni0.37 The evaluation of the formation/sta bility of the Fe-Ni phases formed under irradiation with different ion s and doses was followed by conversion electron Mossbauer spectroscopy . The magnetic hysteresis curves were also obtained in order to correl ate the hyperfine pattern with magnetic properties. The as-deposited s ample reveals mainly the characteristic alpha-Fe while He- and Ne-irra diated samples clearly show a phase transformation with segregation of gamma-FeNi phases with different Ni concentrations, a magnetic atomic ally ordered phase (similar to 50% Ni), and a nonmagnetic phase (less than or equal to 30% Ni). However, mixing with Ne is more effective th an with He for similar doses. The results obtained with Xe showed a la rge distribution of hyperfine fields similarly to previous results rep orted for Kr [C. Tosello, F. Ferrari, R. Brand, W. Keune, G. Marest, M . A. El Khakani, J. Parellada, G. Principi, S. Lo Russo, V. Rigato, an d S. Enzo, Nucl. Instrum. Methods B 80/81, 417 (1993)]. (C) 1997 Ameri can Institute of Physics.