Terahertz spectroscopy of spin excitations in magnetoelectric LiFePO4 in high magnetic fields

  • We investigated the spin excitations of magnetoelectric LiFePO4 by THz absorption spectroscopy in magnetic fields up to 33 T. By studying their selection rules, we found not only magnetic-dipole, but also electric-dipole active (electromagnons) and magnetoelectric resonances. The magnetic field dependence of four strong low-energy modes is reproduced well by a four-spin mean-field model for fields applied along the three orthorhombic axes. From the fit of magnetization and magnon frequencies, we refined the exchange couplings, single-ion anisotropies, and the Dzyaloshinskii-Moriya interaction parameters. Additional spin excitations not described by the mean-field model are observed at higher frequencies. Some of them show a strong shift with the magnetic field, up to 4 cm−1 T−1, when the field is applied along the easy axis. Based on this field dependence, we attribute these high frequency resonances to the excitation of higher spin multipoles and of two magnons, which becomeWe investigated the spin excitations of magnetoelectric LiFePO4 by THz absorption spectroscopy in magnetic fields up to 33 T. By studying their selection rules, we found not only magnetic-dipole, but also electric-dipole active (electromagnons) and magnetoelectric resonances. The magnetic field dependence of four strong low-energy modes is reproduced well by a four-spin mean-field model for fields applied along the three orthorhombic axes. From the fit of magnetization and magnon frequencies, we refined the exchange couplings, single-ion anisotropies, and the Dzyaloshinskii-Moriya interaction parameters. Additional spin excitations not described by the mean-field model are observed at higher frequencies. Some of them show a strong shift with the magnetic field, up to 4 cm−1 T−1, when the field is applied along the easy axis. Based on this field dependence, we attribute these high frequency resonances to the excitation of higher spin multipoles and of two magnons, which become THz-active due to the low symmetry of the magnetically ordered state.show moreshow less

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Metadaten
Author:L. Peedu, V. Kocsis, D. Szaller, B. Forrai, S. Bordács, István KézsmárkiORCiDGND, J. Viirok, U. Nagel, B. Bernáth, Dmytro KamenskyiORCiDGND, A. Miyata, O. Portugall, Y. Tokunaga, Y. Tokura, Y. Taguchi, T. Rõõm
URN:urn:nbn:de:bvb:384-opus4-995046
Frontdoor URLhttps://opus.bibliothek.uni-augsburg.de/opus4/99504
ISSN:2469-9950OPAC
ISSN:2469-9969OPAC
Parent Title (English):Physical Review B
Publisher:American Physical Society (APS)
Place of publication:College PK
Type:Article
Language:English
Year of first Publication:2022
Publishing Institution:Universität Augsburg
Release Date:2022/11/22
Volume:106
Issue:13
First Page:134413
DOI:https://doi.org/10.1103/physrevb.106.134413
Institutes:Mathematisch-Naturwissenschaftlich-Technische Fakultät
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Physik
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Physik / Lehrstuhl für Experimentalphysik V
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):Deutsches Urheberrecht