Epitaxial L10-ordered NiPt(001)/FePt(001) bi-layers were co-deposited onto MgO(100) substrates via molecular beam epitaxy. The L10 order parameter was high, with concentration modulation along the growth direction. Some FeNiPt0(001) thin films were obtained by interdiffusion of the bilayers. The long-range-order parameter was conserved after interdiffusion (S = 0.75), which could be explained by different mechanisms: a second-neighbour jump, a six-jump cycle, an anti-structural bridge mechanism or an antisite-pair elimination and creation mechanism, a double vacancy or a triple defect diffusion mechanism. Quenched molecular dynamics calculations in the frame of the second moment approximation of the tight binding method were performed to obtain the energetic paths of the different mechanisms. The second neighbour vacancy jump, the simultaneous jumps of bivacancies and the triple defect mechanisms could be ruled out for energetic reasons.

Interdiffusion of Two L10 Phases Without Long-Range Order Decrease: Experiments and Molecular Dynamics Simulations. Goyhenex, C., Montsouka, R.V.P., Kozlowski, M., Pierron-Bohnes, V.: Solid State Phenomena, 2007, 129, 59-66