Regensburg 2013 – scientific programme
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MA: Fachverband Magnetismus
MA 17: Magnetic Particles and Clusters (jointly with CPP, BP)
MA 17.7: Talk
Tuesday, March 12, 2013, 11:45–12:00, H22
Ab initio spin-dynamics for nanostructures with application to domain walls through a Co nanocontact — Laszlo Balogh1, •Laszlo Udvardi1, Krisztian Palotas1, Laszlo Szunyogh1, and Ulrich Nowak2 — 1Department of Theoretical Physics and Condensed Matter Research Group of the Hungarian Academy of Sciences, Budapest University of Technology and Economics, H-1111 Budapest, Hungary — 2Department of Physics, University of Konstanz, 78457 Konstanz, Germany
To calculate the magnetic ground state of nanoparticles we present a self-consistent first-principles method in terms of a fully relativistic embedded cluster multiple scattering Greens function technique. Based on the derivatives of the band energy, a Newton-Raphson algorithm is used to find the ground-state configuration. An extension of the method to finite temperatures is also presented.
The method is applied to a cobalt nanocontact that turned out to show a cycloidal domain wall configuration between oppositely magnetized leads. We found that a wall of cycloidal spin structure is about 30 meV lower in energy than the one of helical spin structure. A detailed analysis revealed that the uniaxial on-site anisotropy of the central atom is mainly responsible to this energy difference. The huge uniaxial anisotropy energy is accompanied by an enhancement and anisotropy of the orbital magnetic moment of the central atom. By varying the magnetic orientation at the central atom, we identify various on-site anisotropy terms and also those due to higher order spin interactions.