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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2511.10396 |
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| _version_ | 1866908658969870336 |
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| author | Dubrovin, R. M. Brulev, A. I. Vovk, N. R. Eliseyev, I. A. Novikova, N. N. Chernyshev, V. A. Smirnov, A. N. Davydov, V. Yu. Wu, Anhua Su, Liangbi Mikhaylovskiy, R. V. Kalashnikova, A. M. Pisarev, R. V. |
| author_facet | Dubrovin, R. M. Brulev, A. I. Vovk, N. R. Eliseyev, I. A. Novikova, N. N. Chernyshev, V. A. Smirnov, A. N. Davydov, V. Yu. Wu, Anhua Su, Liangbi Mikhaylovskiy, R. V. Kalashnikova, A. M. Pisarev, R. V. |
| contents | Linear and non-linear couplings of magnetic and lattice excitations are at the heart of many fascinating magnetophononic phenomena observed in rare-earth orthoferrites, the distinctive feature of which is the tendency to spin-reorientation transitions. Here we report the results of the experimental study of the spin and lattice dynamics in the Brillouin zone center of the rare-earth orthoferrite Sm$_{0.55}$Tb$_{0.45}$FeO$_{3}$ by using polarized infrared reflectivity and Raman scattering spectroscopic techniques. The obtained results were supported by the first-principles calculations, which allowed us to reliably identify the parameters of most infrared- and Raman-active phonons. We reveal the spin-reorientation transitions $Γ_{4}(G_{a}F_{c}) \overset{T_{1}}\longleftrightarrow Γ_{24}(G_{ac}F_{ac}) \overset{T_{2}}\longleftrightarrow Γ_{2}(G_{c}F_{a})$ at $T_{1} \simeq 220$ K and $T_{2} \simeq 130$ K and carefully studied the following evolution of Raman scattering on magnetic excitations at these transitions. Notably, the intermediate magnetic structure $Γ_{24}$ displays an exceptionally broad temperature range $Δ{T} = T_{1} - T_{2} \simeq 90$ K in mixed Sm$_{0.55}$Tb$_{0.45}$FeO$_{3}$ compared to pure rare-earth orthoferrites. We attribute this broadening of the intermediate phase to the modification of the magnetocrystalline anisotropy as a result of the inhomogeneous magnetic structure caused by the random distribution of rare-earth $\mathrm{Sm}^{3+}$ and $\mathrm{Tb}^{3+}$ ions. We found neither change in the parameters of Raman-active $B_{1g}$ phonons nor the appearance of new phonons induced by spin-reorientation transitions, which have been reported in $\mathrm{SmFeO}_{3}$. We assume that our results provide a solid basis for more deeper understanding of magnetophononic phenomena in rare-earth orthoferrites. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_10396 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spin and lattice dynamics at the spin-reorientation transitions in the rare-earth orthoferrite Sm$_{0.55}$Tb$_{0.45}$FeO$_{3}$ Dubrovin, R. M. Brulev, A. I. Vovk, N. R. Eliseyev, I. A. Novikova, N. N. Chernyshev, V. A. Smirnov, A. N. Davydov, V. Yu. Wu, Anhua Su, Liangbi Mikhaylovskiy, R. V. Kalashnikova, A. M. Pisarev, R. V. Materials Science Linear and non-linear couplings of magnetic and lattice excitations are at the heart of many fascinating magnetophononic phenomena observed in rare-earth orthoferrites, the distinctive feature of which is the tendency to spin-reorientation transitions. Here we report the results of the experimental study of the spin and lattice dynamics in the Brillouin zone center of the rare-earth orthoferrite Sm$_{0.55}$Tb$_{0.45}$FeO$_{3}$ by using polarized infrared reflectivity and Raman scattering spectroscopic techniques. The obtained results were supported by the first-principles calculations, which allowed us to reliably identify the parameters of most infrared- and Raman-active phonons. We reveal the spin-reorientation transitions $Γ_{4}(G_{a}F_{c}) \overset{T_{1}}\longleftrightarrow Γ_{24}(G_{ac}F_{ac}) \overset{T_{2}}\longleftrightarrow Γ_{2}(G_{c}F_{a})$ at $T_{1} \simeq 220$ K and $T_{2} \simeq 130$ K and carefully studied the following evolution of Raman scattering on magnetic excitations at these transitions. Notably, the intermediate magnetic structure $Γ_{24}$ displays an exceptionally broad temperature range $Δ{T} = T_{1} - T_{2} \simeq 90$ K in mixed Sm$_{0.55}$Tb$_{0.45}$FeO$_{3}$ compared to pure rare-earth orthoferrites. We attribute this broadening of the intermediate phase to the modification of the magnetocrystalline anisotropy as a result of the inhomogeneous magnetic structure caused by the random distribution of rare-earth $\mathrm{Sm}^{3+}$ and $\mathrm{Tb}^{3+}$ ions. We found neither change in the parameters of Raman-active $B_{1g}$ phonons nor the appearance of new phonons induced by spin-reorientation transitions, which have been reported in $\mathrm{SmFeO}_{3}$. We assume that our results provide a solid basis for more deeper understanding of magnetophononic phenomena in rare-earth orthoferrites. |
| title | Spin and lattice dynamics at the spin-reorientation transitions in the rare-earth orthoferrite Sm$_{0.55}$Tb$_{0.45}$FeO$_{3}$ |
| topic | Materials Science |
| url | https://arxiv.org/abs/2511.10396 |