  We studied the effect of dopants (Al, Ti, Zr) on the thermal stability of
iron nitride thin films prepared using a dc magnetron sputtering technique.
Structure and magnetic characterization of deposited samples reveal that the
thermal stability together with soft magnetic properties of iron nitride thin
films get significantly improved with doping. To understand the observed
results, detailed Fe and N self-diffusion measurements were performed. It was
observed that N self-diffusion gets suppressed with Al doping whereas Ti or Zr
doping results in somewhat faster N diffusion. On the other hand Fe
self-diffusion seems to get suppressed with any dopant of which heat of nitride
formation is significantly smaller than that of iron nitride. Importantly, it
was observed that N self-diffusion plays only a trivial role, as compared to Fe
self-diffusion, in affecting the thermal stability of iron nitride thin films.
Based on the obtained results effect of dopants on self-diffusion process is
discussed.
