Dresden 2020 – scientific programme

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MA: Fachverband Magnetismus

MA 2: Ultrafast Magnetization I

MA 2.10: Talk

Monday, March 16, 2020, 12:00–12:15, HSZ 101

Laser excitation induced ultrafast demagnetization and perpendicular magnetic anisotropy reduction in a Co₈₈Tb₁₂ thin film — •Marcel Hennes¹, Alaa el dine Merhe¹, Valentin Chardonnet¹, Xuan Liu¹, Clemens von Korff Schmising³, Benoît Mahieu⁴, Michel Hehn⁵, Gregory Malinowski⁵, Flavio Capotondi⁶, Emanuele Pedersoli⁶, Emmanuelle Jal¹, Jan Lüning^1,2, and Boris Vodungbo¹ — ¹Sorbonne Université - LCPMR, CNRS, Paris, France — ²Synchrotron SOLEIL, Gif-sur-Yvette, France — ³Max-Born-Institut, Berlin, Germany — ⁴Laboratoire d’Optique Appliquée (LOA), Palaiseau, France — ⁵Institut Jean Lamour (IJL), Nancy, France — ⁶FERMI, Elettra-Sincrotrone, Trieste, Italy

We use time resolved resonant magnetic x-ray scattering experiments, performed at the Co M- and Tb O-edge, to study laser-induced demagnetization effects in a ferrimagnetic Co₈₈Tb₁₂ alloy with magnetic stripe domain structure. We evidence an ultrafast decrease of magnetization on sub-ps timescales in the Co as well as in the Tb sublattice and we provide a quantitative description of the demagnetization behavior. Combining the femtosecond temporal with nanometer spatial resolution of our pump-probe experiments, we show that on ultrashort timescales (<1 ps), no detectable change in domain size and domain wall size occurs. However, we evidence a broadening of the domain walls, setting in after approximately 4 ps, which we attribute to a decrease of the uniaxial anisotropy due to energy transfer to the lattice.