Magnetization reversal processes in epitaxial Co/Fe bi-layers grown on MgO(001).
We report on the mechanism of magnetization reversal in epitaxial Co/Fe bi-layers grown by molecular beam epitaxy on MgO(001) substrates. For Co films thicker than 5 nm, the crystal structure is hexagonal. The Fe layer follows an epitaxial relation relative to the MgO substrate of (001)[100]Fe//(001)[110]MgO. When deposited on a cubic Fe layer, the Co layer follows a bi-crystal epitaxial relation of (11{bar 2}0)[0001]Co//(001) 100 Fe as previously reported [Popova et al., Appl. Phys. Lett. 81, 1035 (2002); Wang et al., J. Appl. Phys. 101, 09D103 (2007)]. The magnetization reversal in-plane follows a cubic fourfold symmetry, which coincides with that of the underlying bcc Fe layer. In this study, we find that the area of each Co crystal domain spans 200-1500 nm{sup 2} and that these two domains are approximately evenly distributed. The micromagnetic reversal mechanism is a combination of coherent rotational processes and domain wall displacement. These magnetic domains are sized tens of {micro}m and separated by predominately 90{sup o} or occasionally 180{sup o} domain walls along the Fe<110> and Fe<100> directions, respectively. The cubic anisotropy of the bi-crystalline Co layer is explained by exchange-coupling between hcp grains with perpendicular crystallographic orientation, each having in-plane uniaxial magnetic anisotropy along its respective [0001] direction.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- SC; Engineering and Physical Sciences Research Council; Royal Academy of Engineering
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1004863
- Report Number(s):
- ANL/MSD/JA-68846
- Journal Information:
- J. Appl. Phys., Journal Name: J. Appl. Phys. Journal Issue: Mar. 2008 Vol. 103; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- ENGLISH
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