From electronic structure to magnetisation dynamics

In this talk, a computationally efficient scheme is outlined to evaluate all needed parameters to perform simulations of magnetization dynamics, both on an atomistic level as well as on a micromagnetic level. Examples of calculated Heisenberg exchange interaction, Dzyaloshinskii-Moriya (DM) interaction and the Gilbert damping parameter will be given. The accuracy of these parameters is addressed by calculating theoretical spin-wave spectra using them, and to compare these spectra to measured values. In the talk, possible microscopic mechanisms that determine the influence of these parameters will be discussed, involving non-collinear contributions to the DM interaction as well as mechanisms behind anisotropies of the Gilbert damping parameter. In addition, extension of atomistic spin-dynamics simulations to coupled spin-lattice dynamics will be presented, as well a multiscale method that connects an atomistic and micromagnetic description of the magnetization dynamics. These simulation tools open the door for a quantitative description and understanding of the microscopic origin of many fundamental phenomena of contemporary interest, such as ultrafast demagnetization and magnetocalorics, and results from such simulations will be presented.