Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 17: PhD Symposium: Ultrafast spin-lattice interactions (joint session MA/AKjDPG)

MA 17.1: Hauptvortrag

Dienstag, 13. März 2018, 09:35–10:20, H 1012

Understanding spin and lattice interactions at ultrafast timescales — •Peter M. Oppeneer — Uppsala University, S-75120 Uppsala, Sweden

The interactions between spin moments and the crystal lattice are, in thermal equilibrium, responsible for a variety of phenomena, such as magnetostriction, magnetoelasticity, spin-reorientation transitions etc. In recent years these fundamental interactions are being probed on ultrafast timescales, which has led to discoveries of unexpected phenomena, as e.g. ultrafast demagnetization, breaking of exchange interactions, spin currents and all-optical switching. A characteristic feature of these discoveries is that an ultrashort excitation initiates highly correlated, out-of-equilibrium interactions of electrons, spins, and ions.

In this overview I survey the current understanding of ultrafast processes involving spins, phonons and hot electrons, aiming to go beyond a purely phenomenological picture and achieve atomistic theory. I shall address electron-phonon spin dissipation in the context of ultrafast laser-induced demagnetization, multiscale modeling of breaking of the exchange interaction, and helicity-induced all-optical switching. A second emerging area concerns ultrafast nonequilibrium energy flow between hot electrons and phonons; recent results emphasize that this flow proceeds in a manner different from the commonly used two-temperature model, and that therefore new theoretical modeling is required to capture the nonequilibrium electron-spin-lattice interplay.