Effect of additional Au layer on ordering processes in FePt alloy films on and without substrates during high-temperature annealing.

The effect of the location of an additional Au layer (top, intermediate, and bottom) on the residual stresses, structure, the transformation of the disordered A1 phase into the ordered L1₀ FePt phase, and magnetic properties of layered FePt(15 nm)-Au films on SiO₂(100 nm)/Si(001) substrate is investigated. The ordering processes in the films separated from the substrates during in situ annealing are studied as well. It is shown that the level of mechanical stresses depends on the Au layer location and the number of interfaces in FePt–Au films. Both films (on the substrate and separated from it) with an intermediate Au layer had the lowest temperature of the beginning of L1₀ phase formation. During annealing, diffusion of Au and its redistribution along the grain boundaries of the L1₀ FePt phase occur. An increase in the Au concentration along the grain boundaries reduces the exchange interaction between them and increases the coercivity of the FePt/Au and Au/FePt films. [ABSTRACT FROM AUTHOR]