Ion-irradiation-induced chemical ordering of intermetallic alloys – Predictions based on atomistic simulations

The L10 transition temperatures for chemical ordering in FePd and FePt intermetallic alloys may be substantially reduced by ion irradiation [1]. Alignment of the strong magnetic axis normal to the surface layer was achieved. Recently, we showed via kinetic Monte Carlo simulations [2] that (i) ion-beam-induced reduction of the L10 transition temperature may be understood in terms of vacancy-assisted atomic ordering and that (ii) superstructure alignment results from a small initial directional short range order (DSRO).
In this contribution (i) we present systematic studies of the ion-irradiation-induced L10 ordering in thin layers, (ii) we predict the evolution of chemical ordering in layers with well-designed initial DSRO, (iii) we study in non-stoichiometric alloys (e.g. Fe1-xPdx) the competition of L10 ordering (FePd) with L12 ordering (Fe3Pd), (iv) we extend our atomistic simulations of ion-irradiation-induced ordering to more complex systems like Heusler alloys and (v) we evaluate the influence of interfaces in nanostructures on the ordering process.
[1] D. Ravelosona, C. Chappert, V. Mathet and H. Bernas, Appl. Phys. Lett. 76 (2000) 236.
[2] H. Bernas, J.-Ph. Attane, K.-H. Heinig, D. Halley, D. Ravelosona, A. Marty, P. Auric, C. Chappert, Y. Samson, Phys. Rev. Lett. 91 (2003) 77203.