Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 13: Surface Magnetism

MA 13.4: Vortrag

Dienstag, 26. Februar 2008, 11:15–11:30, EB 301

Giant positive magneto-crystalline anisotropy in ferromagnetic Mn/W(001) overlayer. — Martin Ondraček, Alexander Shick, •František Máca, and Tomas Jungwirth — Institute of Physics ASCR, Prague, Czech Republic

Proposal of the ferromagnetic (FM) ground state for Mn monatomic overlayer on W(001) is reported recently by Ferriani et al. [1] on the basis of first-principles calculations. We study the magneto-crystalline anisotropy (MAE), spin (M_S) and orbital (M_L) magnetic moments, and tunneling anisotropic magneto-resistance (TAMR) of FM-Mn/W(001). The anisotropic properties of Mn/W(001) were investigated making use of the relativistic version of the FP-LAPW method [2], in which SO coupling is included in a self-consistent second-variational procedure. The magnetic force theorem was used to evaluate the MAE and the DOS anisotropy.For the Mn atom, out-of-plane M_S=3.18 µ_B and M_L = 0.09 µ_B are calculated. There is a strong induced W-interface M_S=−0.34 µ_B and M_L=−0.06 µ_B. The spin and orbital polarizations of W are quickly decaying away from the interface, showing slow oscillations. When the magnetization is rotated in-plane, there is no anisotropy in M_S, and a pronounced reduction of in-plane M_L. Accordingly, the very big positive MAE of 5.6 meVper Mn-atom is calculated, which is shown to originate from the W contribution. In addition, the TAMR is estimated from the densities of states anisotropy. [1] Ferriani P., Heinze, S., Bihlmayer, G., Blügel, S., Phys. Rev. B 72 (2005), 024452. [2] A.B. Shick, D.L. Novikov, and A.J. Freeman, Phys. Rev. B 56,R14259 (1997).