Dependence of ordering kinetics of FePt thin films on different substrates

FePt thin films are deposited on SrTi[O.sub.3], MgO, and a 2 nm-[O.sub.x] underlayer on an Si substrate at room temperature and then annealed at elevated temperatures. Studies of the [L1.sub.0] ordering process in each case show that the ordering temperature for the FePt film on the nonepitaxial Si/Fe[O.sub.x] substrate is ~150 [degrees]C lower than the epitaxial FePt films deposited on MgO and SrTi[O.sub.3] substrates. We argue that internal stresses arising from lattice defects and a recrystallizing process as well as thermal strain from differences in thermal expansion between substrate and film are responsible for the differences in ordering kinetics from the A1 to [L1.sub.0] phase of FePt on the various substrates. Index Terms--Epitaxial growth, FePt, nonepitaxial growth, ordering kinetics.