Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 23: Focus Session: Magneto-Transport and Magneto-Optics of Higher Orders in Magnetization I

MA 23.6: Talk

Wednesday, March 19, 2025, 11:45–12:00, H20

Polarization variation method for investigation of magnetic and magneto-optical anisotropies — •Tomáš Ostatnický, Zeynab Sadeghi, Jozef Kimák, Peter Kubaščík, Eva Schmoranzerová, Lukáš Nádvorník, František Trojánek, and Petr Němec — Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic

We present a newly developed method for all-in-one measurement of both magnetic anisotropy and anisotropy of magneto-optical (MO) coupling in magnetic materials. It fully relies on the quadratic MO response (in magnetization) of a sample. The method works in both the reflection and transmission at near-normal incidence, it is not limited by presence of components with linear MO response in setup and it does not require sample rotation during the experiment; it therefore allows measurements with a sample placed inside a cryostat. Measurement scheme is based on a scanning of the probe beam polarization change upon rotation of external magnetic field for several linear polarization of the probe laser. Numerical analysis of the full set of data allows us to recover magnitude and anisotropy of the MO coupling coefficient and we further determine the magnetic anisotropy of the sample by a fitting procedure. We demonstrate the precision of the method by characterizing several GaMnAs ferromagnetic samples with different Mn contents. Reliability of the method is confirmed by a perfect fit of the MO coupling constants with the predictions based on the G-tensor formalism and by a mutual agreement of magnetic anisotropic constants, determined from data acquired at different wavelengths.