Regensburg 2010 – wissenschaftliches Programm

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KR: Fachverband Kristallographie

KR 10: Poster: Multiferroics (with MA, DF, KR, DS)

KR 10.69: Poster

Dienstag, 23. März 2010, 10:45–13:45, Poster A

Interplay between magnetism, structure and chemical order in small CoPt clusters: Ab initio and model calculations — •Lucila Juárez-Reyes, Jesus Dorantes-Dávila, and Gustavo Pastor — Institut für Theoretische Physik, Universität Kassel, Germany

The magnetic properties of small Co_NPt_M clusters (N+M≤ 5) are studied using a generalized gradient approximation to the density functional theory (DFT) and a self-consistent tight-binding (SCTB) model. First, we perform a systematic study of all posible different topological geometries, spin-moment configurations and chemical orders in the framework of the DFT. Second, by using the optimal ab initio structures we determine the spin moments, orbital moments and magnetic anisotropy energy within the SCTB method. The DFT calculations yield compact structures with particularly short bond lengths among the Co atoms (d_Co−Co≃ 2.2−2.4Å). Pt doping induces an important enhancement of the Co spin moments µ_Co which are about 0.25 µ_B larger than µ_Co in Co_N. This is mainly due to important charge transfers between the Co and Pt atoms. SCTB calculations show a 15–20 % orbital contibution to the total magnetic moment. Finally, a non trivial dependence of the MAE landscape on Pt concentration is observed.