S. A. Klimin, A. D. Molchanova, V. A. Chernyshev, V. N. Denisov, N. N. Novikova, V. A. Yakovlev, “Spectroscopic study of the multiferroic LiCoPO<nobr>$_4$</nobr>: magnetostructural phase transition”, Pis'ma v Zh. Èksper. Teoret. Fiz., 2025, Volume 121, Issue 3,Pages <nobr>202

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Spectroscopic study of the multiferroic LiCoPO$_4$: magnetostructural phase transition

S. A. Klimin^a, A. D. Molchanova^a, V. A. Chernyshev^b, V. N. Denisov^ac, N. N. Novikova^a, V. A. Yakovlev^a

^a Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow, 108840 Russia
^b Ural Federal University named after the first President of Russia Boris Yeltsin, Yekaterinburg, 620062 Russia
^c Technological Institute of Superhard and New Carbon Materials, National Research Center Kurchatov Institute, Troitsk, Moscow, 108840 Russia

Abstract: The low-frequency excitations of the LiCoPO$_4$ multiferroic have been studied. New lines of various origins have been observed in the transmission spectra below the temperature of antiferromagnetic ordering, which is accompanied by the appearance of spontaneous electric polarization. Most of these lines correspond to magnetic excitations. The appearance of new phonons in the antiferromagnetic state has been detected for the first time, which makes it possible to classify the phase transition as a magnetostructural phase transition. Information on the frequencies of infrared-active $B_{1u}$ and $B_{2u}$ modes of LiCoPO$_4$ has been obtained for the first time. These data are in good agreement with the ab initio calculations.

Received: 11.11.2024
Revised: 28.11.2024
Accepted: 09.12.2024

DOI: 10.31857/S0370274X25020051