Antiferro octupolar order in the 5d$^1$ double perovskite Sr$_2$MgReO$_6$ and its spectroscopic signatures
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| Format: | Preprint |
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2025
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| _version_ | 1866910900215087104 |
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| author | Mosca, Dario Fiore Pourovskii, Leonid V. |
| author_facet | Mosca, Dario Fiore Pourovskii, Leonid V. |
| contents | "Hidden"-order phases with high-rank multipolar order parameters have been recently detected in several cubic double perovskites of 5$d$ transition metals. Here, by constructing and solving an ab initio low-energy Hamiltonian, we show that an antiferroic order of magnetic octupoles also forms in the tetragonal 5d$^1$ double perovskite Sr$_2$MgReO$_6$. The low-temperature order in this material is determined by a tetragonal crystal field dominating over exchange interactions. This results in a well isolated crystal-field doublet ground state hosting octupolar low-energy degrees of freedom. Very weak dipole moments entangled with the primary octupole order parameters are induced by admixture of the excited $j1/2$ spin-orbit multiplet. We show that the octupolar order leads to characteristic quasi-gapless magnetic excitation spectra as well as to the intensity of superstructural neutron diffraction reflexes peaking at large scattering momenta. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2504_00105 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Antiferro octupolar order in the 5d$^1$ double perovskite Sr$_2$MgReO$_6$ and its spectroscopic signatures Mosca, Dario Fiore Pourovskii, Leonid V. Strongly Correlated Electrons Materials Science "Hidden"-order phases with high-rank multipolar order parameters have been recently detected in several cubic double perovskites of 5$d$ transition metals. Here, by constructing and solving an ab initio low-energy Hamiltonian, we show that an antiferroic order of magnetic octupoles also forms in the tetragonal 5d$^1$ double perovskite Sr$_2$MgReO$_6$. The low-temperature order in this material is determined by a tetragonal crystal field dominating over exchange interactions. This results in a well isolated crystal-field doublet ground state hosting octupolar low-energy degrees of freedom. Very weak dipole moments entangled with the primary octupole order parameters are induced by admixture of the excited $j1/2$ spin-orbit multiplet. We show that the octupolar order leads to characteristic quasi-gapless magnetic excitation spectra as well as to the intensity of superstructural neutron diffraction reflexes peaking at large scattering momenta. |
| title | Antiferro octupolar order in the 5d$^1$ double perovskite Sr$_2$MgReO$_6$ and its spectroscopic signatures |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2504.00105 |