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MA: Fachverband Magnetismus

MA 38: Ultrafast Magnetization Effects III

MA 38.4: Vortrag

Donnerstag, 21. März 2024, 12:00–12:15, EB 202

Nonlinearities in ultrafast transverse magneto-optical Kerr effect spectroscopy — •Johanna Richter, Somnath Jana, Ole Zülich, Daniel Schick, Clemens von Korff-Schmising, and Stefan Eisebitt — Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy

Ultrafast magneto-optical Kerr effect spectroscopy (T-MOKE) in the extreme ultraviolet spectral range provides detailed insight into element-specific magnetization dynamics and has become a powerful experimental technique for unravelling the fundamental microscopic processes occurring in laser-excited magnetic materials.

In this work, we investigate the relationship between the T-MOKE observable (magnetic asymmetry) and the element-specific magnetization by calculating the exact response based on a wave propagation algorithm. We present detailed simulations for realistic magnetic multilayers as a function of incident angle and photon energies between 40 eV and 72 eV and find pronounced deviations in the proportionality between magnetization and asymmetry. These findings reproduce time-resolved measurements exhibiting strong nonlinearities, including situations where the asymmetry increases despite of a decreasing magnetization. We introduce a metric to quantify these nonlinearities and identify sample structures and T-MOKE geometries where a direct proportionality between T-MOKE measurements and magnetization remains a good approximation, and show how our data methodology allows a correct interpretation of T-MOKE experiments.

Keywords: Ultrafast magnetization dynamics; XUV spectroscopy; Transverse Magneto-Optical Kerr Effect (T-MOKE); Element-Specific Magnetization; Magnetic Asymmetry