Regensburg 2025 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 4: Electron Theory of Magnetism and Correlations
MA 4.4: Vortrag
Montag, 17. März 2025, 10:15–10:30, H19
Magnetic-circular dichroism on low-lying excitations in antiferromagnetic Fe2Mo3O8 — •Kirill Vasin1, Istvan Kézsmárki1, Sándor Bordács2, and Joachim Deisenhofer1 — 1University of Augsburg, Augsburg, Germany — 2Budapest University of Technology and Economics, Budapest, Hungary
We report the observation of a strong magnetic circular dichroism (MCD) and Faraday effect in the polar honeycomb antiferromagnet Fe2 Mo3 O8 in the terahertz (THz) range. Using a common linear detection scheme with polarizers on both the emitter and detector set to the same angle, we observe seemingly thickness-dependent features and broadening in the transmission spectrum near narrow resonances in the Faraday configuration. These features are absent in the Voigt geometry with the same static magnetic field configuration, confirming that they arise from Faraday rotation (or MCD). By analyzing the zero-field spectrum and fitting Lorentz oscillators in the time-domain, we resolved oscillators parameters of the observed strong and narrow THz excitations with high accuracy. Using these parameters, we successfully reconstructed our field- and thickness-dependent transmission spectra, highlighting the role of Faraday rotation in the observed phenomena.
Our findings demonstrate the importance of considering detection schemes in Time-Domain THz spectroscopy and provide insights into methods of measuring MCD and Faraday rotation without ellipsometry techniques in <<single-shot>> transmission measurements for aniferromagnets.
Keywords: faraday effect; magnetic circular dichroism; antiferromagnets; time-domain spectroscopy; transmission spectroscopy