SKM 2023 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 30: PhD Focus Session: Non-equilibrium dynamics in theory and experiment

MA 30.1: Hauptvortrag

Mittwoch, 29. März 2023, 15:00–15:30, HSZ 02

Femto- phono- magnetism — •Sangeeta Sharma — Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Str. 2A, 12489 Berlin, Germany

From the outset of research into femtomagnetism, the field in which spins are manipulated by light on femtosecond or faster time scales, several questions have arisen and remain highly debated: How does the light interact with spin moments? How is the angular momentum conserved between the nuclei, spin, and angular momentum during this interaction? What causes the ultrafast optical switching of magnetic structures? What is the ultimate time limit on the speed of spin manipulation? What is the impact of nuclear dynamics on the light-spin interaction?

In my talk I will advocate a parameter free ab-initio approach to treating ultrafast light-matter interactions, and discuss how this approach has led both to new answers to these old questions but also to the uncovering of novel and hitherto unsuspected early time spin dynamics phenomena. In particular I will show that selective excitation of phonon modes exert a strong influence on femtosecond demagnetisation. Our finding demonstrates that the nuclear system, typically assumed to play a role of an energy sink aiding remagnetization of the spin system, plays a profound role in controlling femtosecond demagnetization of magnetic materials.