Guardado en:
| Autores principales: | , , , , , , , , , , , |
|---|---|
| Formato: | Recurso digital |
| Lenguaje: | |
| Publicado: |
Zenodo
2025
|
| Acceso en línea: | https://doi.org/10.1021/jacs.5c13048 |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
Tabla de Contenidos:
- <p>We report a highly symmetric <strong>{Gd</strong><sub><strong>9</strong></sub><strong>}</strong>molecular nanocage with the formula [Gd<sub>9</sub>(BA)<sub>16</sub>(OH)<sub>10</sub>]Cl·3(C<sub>2</sub>H<sub>5</sub>OH)·4(H<sub>2</sub>O), which crystallizes in the cubic space group <em>Pn</em>3̅<em>n</em>. The structure features two crystallographically distinct Gd<sup>3+</sup> ions, forming highly regular triangular Gd<sup>3+</sup>arrangements leading to a geometrically frustrated magnetic network. Magnetization measurements at 2 K reveal a broad plateau between 1.5 and 4 T, while zero-field heat capacity shows a Schottky anomaly centered at 0.6 K─indicative of low-lying excited states and competing magnetic interactions. The magnetocaloric effect, evaluated through both direct and indirect methods, exhibits a re-entrant profile in the isentropic curves, pointing to a nontrivial evolution of magnetic entropy under applied fields. To probe the origin of this behavior, we employed the finite-temperature Lanczos method on a model spin Hamiltonian. The results reveal that the antiferromagnetic exchange between Gd<sup>3+</sup> ions, combined with the frustration inherent to the <strong>{Gd</strong><sub><strong>9</strong></sub><strong>}</strong> geometry, leads to a degenerate ground state. An external field lifts this degeneracy, producing a regime with a sharply reduced density of states between 1.5 and 4 K, which underlies the unconventional magnetocaloric response. The <strong>{Gd</strong><sub><strong>9</strong></sub><strong>}</strong>cage thus represents a rare example of a spin-frustrated arrangement arising from competing antiferromagnetic interactions between the Gd<sup>3+</sup>. These findings demonstrate how frustrated topologies and tunable low-energy excitations can be exploited to modulate the magnetothermal properties, with potential implications for cryogenic magnetic cooling technologies.</p>