Dynamical Magnetic Excitations of Nanostructures from First Principles

Within time-dependent density functional theory, combined with the Korringa-Kohn-Rostoker Green functions, we devise a real space method to investigate spin dynamics. Our scheme enables one to deduce the Coulomb potential which assures a proper Goldstone mode is present. We illustrate with application to $3d$ adatoms and dimers on Cu(100).

Figure 1

(a) The variation of the product of $U$ with the different values of the moments. The values obtained for the adatoms fall on the diagonal as estimated in the curve of Himpsel [14]. (b) The imaginary part of $\chi$ is plotted for every adatom when applying an additional magnetic field along the $z$ direction corresponding to a Larmor frequency of 13.6 meV (dashed line). (c) $\mathrm{Im}\chi$ calculated for the four dimers. The optical modes, estimated for Mn and Fe from a Heisenberg model, are represented as dashed lines.