  Composition depth profiles of d.c.-plated and pulseplated Fe-Ni alloys have
been investigated with the reverse depth profile analysis method. When d.c.
plating is applied, the mole fraction of iron near the substrate is higher than
during steadystate deposition since iron is preferentially deposited beside
nickel and the achievement of the steadystate deposition condition takes time.
The steadystate composition was achieved typically after depositing a
90-nm-thick alloy layer. In the pulseplating mode, samples with nearly uniform
composition could be obtained at a duty cycle of 0.2 or smaller, and a
continuous change in the composition profile could be seen as a function of the
duty cycle above this value. A constant sample composition was achieved with
pulseplating in a wide peak current density interval. The composition depth
profile was also measured for a wide range of Fe2+ concentration. The different
characteristics of the composition depth profile as a function of the
deposition mode can be explained mostly in terms of mass transport effects. The
elucidation of the results is fully in accord with the kinetic models of
anomalous codeposition and with the assumption of the superposition of a
stationary and a pulsating diffusion layer. The results achieved help to
identify the conditions for the deposition of ultrathin magnetic samples with
uniform composition along the growth direction.
