Implementing Real Ab Initio in Out-of-Equilibrium Dynamics

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The tremendous growth of the information-based society has strongly increased the demand for high-speed electronic devices with low energy consumption. A promising approach is spintronics, in which the spin instead of the charge of the electron is used as information carrier. To realize the required high-speed of spin operations, systems that can be driven strongly and quickly out-of-equilibrium are needed. The mechanisms underlying these fast out-of-equilibrium processes are however poorly understood so far.The aim of this research project is to achieve a new level of understanding by deriving non-equilibrium theory to describe the ultrafast relaxation processes between phonons, electrons, and spin excitations in real materials. To reach this objective I will combine advanced ab initio methods with atomistic and microscopic simulations and thereby develop innovative multiscale theories for the dynamics in laser excited materials on ultrashort time scales beyond current models.I will derive a new model including non-thermal relaxation processes to explore the ultrafast, non-equilibrium interaction of electrons and phonons in typical systems as gold and graphite. Furthermore, I will study the response to ultrafast laser excitation in heterostructure materials. In particular, I want to study light induced spin torques in metallic heterostructures to explore the relevant mechanisms for new applications, as for example metallic terahertz emitters and explore the occurring magnon spin currents after laser excitation of metal/YIG bi- and trilayers. In addition, I shall develop new models to explore the various microscopic mechanisms of electronic spin relaxation in spin dynamics as well as study the coupled dynamics of spin and orbital moments.