Polar phonons and magnetic excitations in the antiferromagnet CoF$_2$
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arXiv
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| Autori principali: | , , , , , , , , |
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| Natura: | Preprint |
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2024
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| author | Dubrovin, R. M. Tellez-Mora, A. Garcia-Castro, A. C. Siverin, N. V. Novikova, N. N. Boldyrev, K. N. Mashkovich, E. A. Romero, Aldo H. Pisarev, R. V. |
| author_facet | Dubrovin, R. M. Tellez-Mora, A. Garcia-Castro, A. C. Siverin, N. V. Novikova, N. N. Boldyrev, K. N. Mashkovich, E. A. Romero, Aldo H. Pisarev, R. V. |
| contents | The coupling between antiferromagnetic spins and infrared-active phonons in solids is responsible for many intriguing phenomena and is a field of intense research with extensive potential applications in the modern devices based on antiferromagnetic spintronics and phononics. Insulating rutile antiferromagnetic crystal CoF$_2$ is one of the model materials for studying nonlinear magnetophononics due to the strong spin-lattice coupling as a result of the orbitally degenerate ground state of Co$^{2+}$ ions manifested in the plethora of static and induced piezomagnetic effects. Here we report results on the complete infrared spectroscopy study of lattice and magnetic dynamics in CoF$_2$ in a wide temperature range and their careful analysis. We observed that infrared-active phonons demonstrate frequency shifts at the antiferromagnetic ordering. Furthermore, using first-principles calculations, we examined the lattice dynamics and disclosed that these frequency shifts are rather due to the spin-phonon coupling than geometrical lattice effects. Next we found that the low-frequency dielectric permittivity demonstrates distinct changes at the antiferromagnetic ordering due to the spontaneous magnetodielectric effect caused by the behavior of infrared-active phonons. In addition, we have observed magnetic excitations in the infrared spectra and identified their magnetodipole origin. To strengthen our conclusions, we analyze the theoretical phonon-magnon coupling overall phonons at the $Γ$ point. We conclude that the largest effect comes from the $A_{1g}$ and $B_{2g}$ Raman-active modes. As such, our results establish a solid basis for further investigations and more deeper understanding of the coupling of phonons with spins and magnetic excitations in antiferromagnets. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2406_15574 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Polar phonons and magnetic excitations in the antiferromagnet CoF$_2$ Dubrovin, R. M. Tellez-Mora, A. Garcia-Castro, A. C. Siverin, N. V. Novikova, N. N. Boldyrev, K. N. Mashkovich, E. A. Romero, Aldo H. Pisarev, R. V. Materials Science The coupling between antiferromagnetic spins and infrared-active phonons in solids is responsible for many intriguing phenomena and is a field of intense research with extensive potential applications in the modern devices based on antiferromagnetic spintronics and phononics. Insulating rutile antiferromagnetic crystal CoF$_2$ is one of the model materials for studying nonlinear magnetophononics due to the strong spin-lattice coupling as a result of the orbitally degenerate ground state of Co$^{2+}$ ions manifested in the plethora of static and induced piezomagnetic effects. Here we report results on the complete infrared spectroscopy study of lattice and magnetic dynamics in CoF$_2$ in a wide temperature range and their careful analysis. We observed that infrared-active phonons demonstrate frequency shifts at the antiferromagnetic ordering. Furthermore, using first-principles calculations, we examined the lattice dynamics and disclosed that these frequency shifts are rather due to the spin-phonon coupling than geometrical lattice effects. Next we found that the low-frequency dielectric permittivity demonstrates distinct changes at the antiferromagnetic ordering due to the spontaneous magnetodielectric effect caused by the behavior of infrared-active phonons. In addition, we have observed magnetic excitations in the infrared spectra and identified their magnetodipole origin. To strengthen our conclusions, we analyze the theoretical phonon-magnon coupling overall phonons at the $Γ$ point. We conclude that the largest effect comes from the $A_{1g}$ and $B_{2g}$ Raman-active modes. As such, our results establish a solid basis for further investigations and more deeper understanding of the coupling of phonons with spins and magnetic excitations in antiferromagnets. |
| title | Polar phonons and magnetic excitations in the antiferromagnet CoF$_2$ |
| topic | Materials Science |
| url | https://arxiv.org/abs/2406.15574 |