Tunnelling, non-collinearity and current-induced switching in metal/heterojunctions

Abstract

Current-induced switching in heterojunctions such as Fe/Vac/Fe and Fe/Ge/Fe, including in the latter case homogeneous and inhomogeneous chemical disorder caused by holes (vacuum), is described theoretically in terms of a multi-scale approach based on ab initio calculations using the fully relativistic screened Korringa–Kohn–Rostoker method and the Landau–Lifshitz–Gilbert equation. It is found that (1) the presence of tunnelling can be a function of the relative angle between the orientations of the magnetization in the magnetic slabs; and (2) disorder is responsible for the occurrence of non-collinear magnetic ground states. Furthermore, it is found that the first terms in the expansion of the twisting energy in a power series in the cosine of this relative angle, namely the interlayer exchange energy term and the anisotropy term, can be used for a qualitative scheme not only to characterize the occurrence of non-collinear ground states, but also for the critical current needed to induce switching.

Acknowledgement

Financial support from Austrian Ministries (GZ 45.531, Zl 98.366) and the TU Vienna is gratefully acknowledged.

Notes

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Additional information

Notes on contributors

P. Weinberger *

Email: [email protected]