Dielectric signatures of crystal-field and low-temperature correlated dynamics in NdMgAl11O19
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2026
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| author | Kumar, Sonu Bastien, Gaël Savinov, Maxim Śliwińska-Bartkowiak, Małgorzata Colman, Ross H. Kamba, Stanislav |
| author_facet | Kumar, Sonu Bastien, Gaël Savinov, Maxim Śliwińska-Bartkowiak, Małgorzata Colman, Ross H. Kamba, Stanislav |
| contents | We report dielectric spectroscopy of single-crystalline \ce{NdMgAl11O19}, a magnetoplumbite hexaaluminate in which localized \ce{Nd^{3+}} moments coexist with a polarizable \ce{AlO5} bipyramidal network. The real part of the permittivity, $\varepsilon'_{c}(T)$, measured along the crystallographic $c$ axis, increases as the temperature is lowered from 275~K to 30~K and is frequency-independent between 4~Hz and 50~kHz. At lower temperatures, a frequency-dependent decrease in permittivity is observed, followed by a further upturn below 2~K. The high-frequency $\varepsilon'_{c}(T)$ is described by a Barrett formula supplemented by an effective two-level contribution, yielding a robust gap of $Δ= 25.85 \pm 0.32$~K consistent with the lowest \ce{Nd^{3+}} crystal-electric-field (CEF) splitting. Below $\sim 30$~K, the dielectric response becomes strongly frequency and magnetic-field dependent. Isothermal $\varepsilon_c'(H)$ measurements reveal a reproducible low-field crossover near $μ_0H_c \simeq 0.85$~T, which we attribute to the competition between antiferromagnetic correlations and Zeeman splitting of the ground-state Kramers doublet. \ce{NdMgAl11O19} thus provides a Kramers reference system in which dielectric signatures of the excited-state CEF manifold can be distinguished from those of the field-tuned, correlation-dominated ground-state doublet sector in a centrosymmetric frustrated magnetoplumbite host |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_24937 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Dielectric signatures of crystal-field and low-temperature correlated dynamics in NdMgAl11O19 Kumar, Sonu Bastien, Gaël Savinov, Maxim Śliwińska-Bartkowiak, Małgorzata Colman, Ross H. Kamba, Stanislav Strongly Correlated Electrons We report dielectric spectroscopy of single-crystalline \ce{NdMgAl11O19}, a magnetoplumbite hexaaluminate in which localized \ce{Nd^{3+}} moments coexist with a polarizable \ce{AlO5} bipyramidal network. The real part of the permittivity, $\varepsilon'_{c}(T)$, measured along the crystallographic $c$ axis, increases as the temperature is lowered from 275~K to 30~K and is frequency-independent between 4~Hz and 50~kHz. At lower temperatures, a frequency-dependent decrease in permittivity is observed, followed by a further upturn below 2~K. The high-frequency $\varepsilon'_{c}(T)$ is described by a Barrett formula supplemented by an effective two-level contribution, yielding a robust gap of $Δ= 25.85 \pm 0.32$~K consistent with the lowest \ce{Nd^{3+}} crystal-electric-field (CEF) splitting. Below $\sim 30$~K, the dielectric response becomes strongly frequency and magnetic-field dependent. Isothermal $\varepsilon_c'(H)$ measurements reveal a reproducible low-field crossover near $μ_0H_c \simeq 0.85$~T, which we attribute to the competition between antiferromagnetic correlations and Zeeman splitting of the ground-state Kramers doublet. \ce{NdMgAl11O19} thus provides a Kramers reference system in which dielectric signatures of the excited-state CEF manifold can be distinguished from those of the field-tuned, correlation-dominated ground-state doublet sector in a centrosymmetric frustrated magnetoplumbite host |
| title | Dielectric signatures of crystal-field and low-temperature correlated dynamics in NdMgAl11O19 |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2604.24937 |