Effect of ion bombardment on the long-range chemical order in FePd films

Fe1-xPdx films of nearly equiatomic composition (0.47 less than or equal to x less than or equal to 0.56) have been prepared by ion-beam sputtering at substrate temperatures T-S=350 degrees C. During growth the films were bombarded by Xe+ ions with energies E(Xe) = 0-100 eV and an ion-to-atom arrival ratio of R = 0.3. Films were characterized by x-ray diffraction and the wavelength dependent magneto-optic Kerr effect. Without bombardment, the films are partly chemically ordered with a long-range order parameter S approximate to 0.7. For energies E(Xe) up to 50 eV the chemical order survives to a high degree and only moderate modifications in the structural data and Kerr spectra are observed, whereas for E(Xe)= 100 eV the chemical order is completely destroyed. In contrast, the epitaxial quality seems to be unaffected by the bombardment for E(Xe)less than or equal to 50 eV. This shows that low-energy ion bombardment during growth only leads to a randomization of the Fe and Pd atoms on the lattice sites without causing significant structural damage. (C) 1996 American Institute of Physics.