Phonon softening and atomic modulations in EuAl$_4$
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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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| _version_ | 1866911782986055680 |
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| author | Korshunov, A. N. Sukhanov, A. S. Gebel, S. Pavlovskii, M. S. Andriushin, N. D. Gao, Y. Moya, J. M. Morosan, E. Rahn, M. C. |
| author_facet | Korshunov, A. N. Sukhanov, A. S. Gebel, S. Pavlovskii, M. S. Andriushin, N. D. Gao, Y. Moya, J. M. Morosan, E. Rahn, M. C. |
| contents | EuAl$_4$ is a rare earth intermetallic in which competing itinerant and/or indirect exchange mechanisms give rise to a complex magnetic phase diagram, including a centrosymmetric skyrmion lattice. These phenomena arise not in the tetragonal parent structure but in the presence of a charge density wave (CDW), which lowers the crystal symmetry and renormalizes the electronic structure. Microscopic knowledge of the corresponding atomic modulations and their driving mechanism is a prerequisite for a deeper understanding of the resulting equilibrium of electronic correlations and how it might be manipulated. Here, we use synchrotron single-crystal X-ray diffraction, inelastic X-ray scattering, and lattice dynamics calculations to clarify the origin of the CDW in EuAl$_4$. We observe a broad softening of a transverse acoustic phonon mode that sets in well above room temperature and, at $T_\mathrm{CDW}=142$ K, freezes out in an atomic displacement mode described by the superspace group $Immm(00γ)s00$. In the context of previous work, our observation is a clear confirmation that the CDW in EuAl$_4$ is driven by electron-phonon coupling. This result is relevant for a wider family of BaAl$_4$ and ThCr$_2$Si$_2$-type rare-earth intermetallics known to combine CDW instabilities and complex magnetism. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2402_15397 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Phonon softening and atomic modulations in EuAl$_4$ Korshunov, A. N. Sukhanov, A. S. Gebel, S. Pavlovskii, M. S. Andriushin, N. D. Gao, Y. Moya, J. M. Morosan, E. Rahn, M. C. Strongly Correlated Electrons Materials Science EuAl$_4$ is a rare earth intermetallic in which competing itinerant and/or indirect exchange mechanisms give rise to a complex magnetic phase diagram, including a centrosymmetric skyrmion lattice. These phenomena arise not in the tetragonal parent structure but in the presence of a charge density wave (CDW), which lowers the crystal symmetry and renormalizes the electronic structure. Microscopic knowledge of the corresponding atomic modulations and their driving mechanism is a prerequisite for a deeper understanding of the resulting equilibrium of electronic correlations and how it might be manipulated. Here, we use synchrotron single-crystal X-ray diffraction, inelastic X-ray scattering, and lattice dynamics calculations to clarify the origin of the CDW in EuAl$_4$. We observe a broad softening of a transverse acoustic phonon mode that sets in well above room temperature and, at $T_\mathrm{CDW}=142$ K, freezes out in an atomic displacement mode described by the superspace group $Immm(00γ)s00$. In the context of previous work, our observation is a clear confirmation that the CDW in EuAl$_4$ is driven by electron-phonon coupling. This result is relevant for a wider family of BaAl$_4$ and ThCr$_2$Si$_2$-type rare-earth intermetallics known to combine CDW instabilities and complex magnetism. |
| title | Phonon softening and atomic modulations in EuAl$_4$ |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2402.15397 |