Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 35: Magnetization / Demagnetization Dynamics II

MA 35.2: Vortrag

Mittwoch, 18. März 2015, 15:15–15:30, EB 301

Element-specific investigation of photo-induced ultrafast demagnetization with light in the visible spectral range — •David Weder, Felix Willems, Oliver Gückstock, Clemens von Korff Schmising, and Stefan Eisebitt — Technische Universität Berlin

A promising approach to control magnetic properties and their sub-picosecond dynamics is photo-induced ultrafast demagnetization which was measured for the first time in 1996 [Beaurepaire1996]. But even after almost 20 years of research the theoretically background about the fundamental microscopic processes has remained unclear. Several competing models describing the underlying mechanisms of laser-induced "femtomagnetism" have been put forward, one of which focuses on spin-polarized superdiffusive electron transport [Battiato2012]. Here, an ultrashort laser pulse triggers non-equilibrium superdiffusive electrons and gives rise to ultrafast transfer of magnetization on a nanometer length scale.

We have established a time-resolved, high-repetition, low-noise optical Kerr setup with micrometer spatial and 100 fs temporal resolution for ultrafast magnetic spectroscopy [KorffSchmising2014]. By nonlinear interaction of the light pulses in a photonic crystal fiber we generate a femtosecond white light continuum which allows us to disentangle the distinct ultrafast transient response of 3d-4f metallic magnetic multilayers and alloys (e.g. CoTb) [Khorsand2013]. We present first results on element specific magnetization dynamics in engineered sample geometries and discuss the influence of spin-polarized electron transport.