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MA: Fachverband Magnetismus

MA 14: Micromagetic Simulation and Electron Theory of Magnetism

MA 14.8: Vortrag

Dienstag, 12. März 2013, 11:15–11:30, H23

Localization of magnetocrystalline anisotropy energy: Answering the Unanswerable — •Ondrej Sipr¹, Sven Bornemann², Hubert Ebert², and Jan Minar² — ¹Institute of Physics ASCR, Cukrovarnicka 10, Prague, Czech Republic — ²Department Chemie, Ludwig-Maximilians-Universitat Munchen, Munchen, Germany

Magnetocrystalline anisotropy is one the of the key properties that determine the practical applicability of various systems containing magnetic atoms and clusters. Calculating it from first principles is a great challenge both numerically and fundamentally. However, to get a full picture, one needs not only to calculate the magnetocrystalline anisotropy energy (MAE) as accurately as possible but also to understand intuitively which factors effect it in various ways. For ad-atoms and films, one of the hotly debated issues in this context is what is the role of the substrate or, in other words, whether the MAE comes from only the magnetic ad-atoms or whether there is also a sizable contribution from the substrate.

In principle, the question about the localization of the MAE cannot be answered because energy is not an extensive quantity. However, by a carefull choice of model systems where the spin-orbit coupling and the exchange field are selectively switched on and off, one can still get a well-defined insight into how different atoms contribute to the "non-localizable" MAE. We illustrate this approach by inspecting the MAE for Co ad-atoms and monolayers on Pd, Pt, Cu, Ag, and Au (111) surfaces calculated under various schemes.