Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 4: Surface Magnetism I
MA 4.7: Vortrag
Montag, 23. März 2009, 12:30–12:45, HSZ 403
Magnetic anisotropy of single 3d atoms on CuN surface — •Alexander B. Shick1, Frantisek Maca1, and Alexander I. Lichtenstein2 — 1Institute of Physics ASCR, Prague, Czech Rep. — 2University of Hamburg, Germany
The magnetic anisotropy energy for Mn, Fe and Co atoms on CuN/Cu(001) surface is investigated making use of the first-principles FP-LAPW calculations and the torque method. For Mn and Fe atoms, the easy magnetization direction is found to be in accord with the experiment [1]. The magnetic anisotropy has a single-ion character and mainly originates from the local magnetic moment of Mn and Fe atoms. The uniaxial magnetic anisotropy constants are calculated in reasonable agreement with the experiment [2].
For Co atom case, the conventional band theory fails to reproduce even qualitatively the experimentally observed magnetic anisotropy [3]. The orbital polarization beyond that given by LSDA has to be included. The effect of the orbital polarization is studied making use of the LDA+U method. The LDA+U induced orbital polarization yields strong enhancement of the orbital component of the magnetic moment for different directions of the Co-atom magnetization and can modify substantially the magnetic anisotropy energy. It is shown that LDA+U induced orbital polarization improves substantially agreement with the experimental magnetic anisotropy energies.
[1] S. Hirjibehedin et al., Science 317, 1199 (2007). [2] A. B. Shick, F. Máca, and A.I. Lichtenstein, arxiv:0810.3389. [3] A. F. Otte et al., Nature Physics 4, 847 (2008).