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arXiv · 1110.2628

Origin of perpendicular anisotropy in thin Co/Pt bilayers grown on alumina

L. Grenet·C. Arm·P. Warin·S. Pouget·A. Marty·A. Brenac·L. Notin·P. Bayle-Guillemaud·M. Jamet
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Abstract

We investigate in this paper the origin of perpendicular anisotropy in Co (1.6 nm)/Pt (3.0 nm) bilayers grown on alumina and annealed up to 650$^{\circ}$C. Above 350$^{\circ}$C, all layers exhibit perpendicular anisotropy. Then coercive fields increase linearly with annealing temperature following two different rates: 0.05 T/100$^{\circ}$C below 550$^{\circ}$C and 0.8 T/100$^{\circ}$C above. By making careful structural characterizations using x-ray diffraction and transmission electron microscopy, we demonstrate the presence of short range correlation of L1$_{1}$ type below 550$^{\circ}$C whereas above 550$^{\circ}$C, L1$_{0}$ chemical ordering is observed. We conclude that perpendicular anisotropy observed in Co/Pt bilayers grown on alumina and annealed may not only be due to interface anisotropy as usually invoked but also to CoPt alloying and chemical ordering that take place during post-growth annealing.

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L. Grenet, C. Arm, P. Warin, S. Pouget, A. Marty, A. Brenac, L. Notin, P. Bayle-Guillemaud, M. Jamet. 2011-10-12. Origin of perpendicular anisotropy in thin Co/Pt bilayers grown on alumina. https://arxiv.org/abs/1110.2628

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