Regensburg 2022 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 29: Multiferroics and Magnetoelectric Coupling (joint session MA/KFM)
KFM 29.3: Vortrag
Donnerstag, 8. September 2022, 15:30–15:45, H47
Microscopic theory of the THz modes and their nonreciprocal directional dichroism in the antiferromagnet Fe2Mo3O8 — •Kirill Vasin1,2, Alexey Nurmukhametov2, Mikhail Eremin2, Anna Strinic1, Lilian Prodan1, Vladimir Tsurkan1, István Kézsmárki1, and Joachim Deisenhofer1 — 1Augsburg University, Augsburg, Germany — 2Kazan, Russia
In the present work, the transmission measurements of a polar dielectric Fe2Mo3O8 were performed by THz time-domain spectroscopy. The origin of the low-lying excitations is not clear, but they were assigned to electromagnons and magnons due to their appearance below TN.
Our microscopic model successfully describes the origin of the optical excitation spectrum in a broad frequency range from the THz to the near-infrared frequency range and the observed dichroism of the low-lying optical modes because of the on-site excitations of the Fe2+ ions in this material. We used the technic of the effective Hamiltonian, including the effects of the crystal field, superexchange interaction and spin-orbit coupling, to model the level schemes of Fe ions projected on the ground configuration of 3d6 electrons.
The directional dichroism in Fe2Mo3O8 can be described by the interference of magnetic and electric-dipole matrix elements, which depend on the applied magnetic field. Our modelled results agrees to the acquired experimental data.