Dresden 2006 – scientific programme

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DS: Dünne Schichten

DS 21: Laser and plasma processes

DS 21.3: Talk

Thursday, March 30, 2006, 17:00–17:15, GER 37

Influence of energetic ions on the L1₀ ordering of FePt films fabricated by magnetron sputtering — •V. Cantelli, J. von Borany, J. Fassbender, and N. Schell — Institute of Ion Beam Physics and Materials Reserarch, Forschungszentrum Rossendorf, P.O.Box 51 01 19, 01314 Dresden

Due to the high uniaxial anisotropy L1₀-ordered FePt is currently the most favoured candidate for future high density storage applications. With respect to a feasible fabrication technology, it is necessary (i) to produce such films on amorphous substrates, and (ii) to enable a low processing temperature (T ≤400^∘C). FePt films deposited at RT only exhibit the face-centered cubic A1-phase. Thus, either deposition or a post-deposition heat treatment at temperatures above typically 500^∘C is required in order to achieve the L1₀-phase. We report on the L1₀-ordering of stoichiometric FePt thin films fabricated on SiO₂/Si substrates by magnetron sputtering at various temperatures (RT- 400^∘C). Using a low deposition rate of approx. 0.6 Å/s and an Ar pressure of 0.3 Pa the ion/atom-ratio during deposition is ≫1 where the ions exhibit energies of about 20 eV. In addition, FePt films have been irradiated subsequently with He ions of 50 keV and fluences between 1x10¹⁵ and 3x10¹⁶ cm⁻² for comparison. The kinetics of A1 → L1₀ transition and ordering have been investigated with in−situ X-ray diffraction at the Synchrotron-beamline ROBL at ESRF. L1₀ ordered FePt films with an ordering parameter S ≥0.8 have been achieved already for an overall process temperature below 350^∘C. The results are discussed in terms of ion-assisted activation and segregation which supports the atomic relocation during L1₀ ordering.