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First-principles study of interlayer exchange coupling and perpendicular magnetic anisotropy in MTJs

Hongxin Yang, Spintec, Grenoble

By using first-principles we studied interlayer exchange coupling (IEC) in Fe|MgO|Fe, Fe|GaAs(ZnSe)|Fe and Fe(Co)|SrTiO3|Fe(Co) magnetic tunnel junctions (MTJs), also the perpendicular magnetic anisotropy at Fe|MgO or Co|MgO interfaces.

In case of IEC in Fe|MgO|Fe MTJs, the influences from structural relaxation and oxidation conditions were investigated. We demonstrated antiferromagnetic (AF) interlayer exchange coupling in relaxed pure Fe|MgO|Fe MTJs, which resolved a long debated explanation for experimental observation. Furthermore, the effect from oxidation condition on IEC was also systematically studied, the result is in a good agreement with previous both theoretical and experimental studies.
In case of Fe|GaAs|Fe and Fe|ZnSe|Fe MTJs, a correlation between the gap opening in the barrier and the type of IEC is demonstrated. As for IEC Fe(Co)|SrTiO3|Fe(Co), I will show you furthermore the effects on IEC from band gap opening in the barrier.

For the perpendicular magnetic anisotropy at FM|MgO interfaces, a mechanism responsible for obtained large PMA was given. Moreover, we demonstrated the correlation between PMA and Bloch states symmetry based spin filtering.