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| Auteurs principaux: | , , , , , , , , , , |
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| Format: | Preprint |
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2026
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| Accès en ligne: | https://arxiv.org/abs/2605.12045 |
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| _version_ | 1866913123945938944 |
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| author | Kumar, N. Rajeesh Khatua, J. Koo, Changhyun Umegaki, Izumi Yin, C. -E. Wang, C. -W. Strydom, A. M. Jeng, H. -T. Choi, Kwang-Yong Sankar, R. Chen, W. -T. |
| author_facet | Kumar, N. Rajeesh Khatua, J. Koo, Changhyun Umegaki, Izumi Yin, C. -E. Wang, C. -W. Strydom, A. M. Jeng, H. -T. Choi, Kwang-Yong Sankar, R. Chen, W. -T. |
| contents | We report a comprehensive investigation of the structural and magnetic properties of Na$_5$Yb(MoO$_4$)$_4$, a member of the stretched diamond magnetic lattice family. Neutron powder diffraction at 3.3~K confirms that the compound crystallizes in the tetragonal \textit{I4$_1$/a} space group, with a large interatomic separation of 6.33~Å between magnetic Yb ions forming a three-dimensional stretched diamond framework. Magnetic susceptibility and specific heat measurements reveal no evidence of long-range magnetic order down to 60~mK. The low-temperature magnetic behavior is governed by an effective $J_{\mathrm{eff}} = 1/2$ Kramers doublet ground state, well separated from excited crystal-field levels, arising from the distorted dodecahedral oxygen coordination of Yb$^{3+}$. Density functional theory calculations within the DFT+$U$ framework indicate that exchange interactions between Yb ions are negligibly small, consistent with the long O--Mo--O super-superexchange pathways. The temperature dependence of the specific heat exhibits signatures of gapped spin excitations, most likely originating from long-range dipolar correlations and further shaped by weak exchange interactions together with the strong single-ion anisotropy of the Yb moments. Muon spin relaxation measurements reveal persistent low-energy spin dynamics, indicating that dipolar correlations remain dynamic and are insufficient to stabilize static magnetic order down to 50~mK. These results identify Na$_5$Yb(MoO$_4$)$_4$ as a rare example of a dipolar quantum paramagnet in which single-ion physics and long-range dipolar interactions dominate, while exchange interactions are suppressed to the millikelvin energy scale. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_12045 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Magnetism and spin dynamics of Na$_5$Yb(MoO$_4$)$_4$: A weakly interacting rare-earth stretched diamond lattice Kumar, N. Rajeesh Khatua, J. Koo, Changhyun Umegaki, Izumi Yin, C. -E. Wang, C. -W. Strydom, A. M. Jeng, H. -T. Choi, Kwang-Yong Sankar, R. Chen, W. -T. Strongly Correlated Electrons Materials Science We report a comprehensive investigation of the structural and magnetic properties of Na$_5$Yb(MoO$_4$)$_4$, a member of the stretched diamond magnetic lattice family. Neutron powder diffraction at 3.3~K confirms that the compound crystallizes in the tetragonal \textit{I4$_1$/a} space group, with a large interatomic separation of 6.33~Å between magnetic Yb ions forming a three-dimensional stretched diamond framework. Magnetic susceptibility and specific heat measurements reveal no evidence of long-range magnetic order down to 60~mK. The low-temperature magnetic behavior is governed by an effective $J_{\mathrm{eff}} = 1/2$ Kramers doublet ground state, well separated from excited crystal-field levels, arising from the distorted dodecahedral oxygen coordination of Yb$^{3+}$. Density functional theory calculations within the DFT+$U$ framework indicate that exchange interactions between Yb ions are negligibly small, consistent with the long O--Mo--O super-superexchange pathways. The temperature dependence of the specific heat exhibits signatures of gapped spin excitations, most likely originating from long-range dipolar correlations and further shaped by weak exchange interactions together with the strong single-ion anisotropy of the Yb moments. Muon spin relaxation measurements reveal persistent low-energy spin dynamics, indicating that dipolar correlations remain dynamic and are insufficient to stabilize static magnetic order down to 50~mK. These results identify Na$_5$Yb(MoO$_4$)$_4$ as a rare example of a dipolar quantum paramagnet in which single-ion physics and long-range dipolar interactions dominate, while exchange interactions are suppressed to the millikelvin energy scale. |
| title | Magnetism and spin dynamics of Na$_5$Yb(MoO$_4$)$_4$: A weakly interacting rare-earth stretched diamond lattice |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2605.12045 |