A Spin Frustrated Hourglass {Gd 9 } Molecular Nanomagnet with Unusual Magnetocaloric Properties

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide We report a highly symmetric {Gd 9 } molecular nanocage with the formula [Gd 9 (BA) 16 (OH) 10 ]Cl·3(C 2 H 5 OH)·4(H 2 O), which crystallizes in the cubic space group Pn 3̅ n . The structure features two crystallographically distinct Gd 3+ ions, forming highly regular triangular Gd 3+ 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 3+ ions, combined with the frustration inherent to the {Gd 9 } 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 {Gd 9 } cage thus represents a rare example of a spin-frustrated arrangement arising from competing antiferromagnetic interactions between the Gd 3+ . 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.

Source: Journal of the American Chemical Society

DOI: 10.1021/jacs.5c13048

Authors: Sai P. K. Panguluri, Eufemio Moreno-Pineda, Concepción Molina-Jirón, Sagar Paul, Marc Ubach I Cervera, Emmanouil K. Charkiolakis, David Gracia, Marco Affronte, Wolfgang Wernsdorfer, Marco Evangelisti, Jürgen Schnack, Mario Ruben

Institutions: Karlsruhe Institute of Technology, Universidad de Panamá, Universidad de Zaragoza, Instituto de Nanociencia y Materiales de Aragón, University of Modena and Reggio Emilia, Istituto Nanoscienze, Bielefeld University, Institut de Science et d'Ingénierie Supramoléculaires

Language: English

Topic: Magnetism in coordination complexes

Subfield: Electronic, Optical and Magnetic Materials

Field: Materials Science

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,500

Funders: Alexander von Humboldt-Stiftung, Ministerio de Ciencia, Innovación y Universidades, Deutsche Forschungsgemeinschaft, Gottfried Wilhelm Leibniz Universität Hannover, Gobierno de Aragón, Leibniz-Gemeinschaft, European Regional Development Fund, Agencia Estatal de Investigación, H2020 Marie Skłodowska-Curie Actions, HORIZON EUROPE Marie Sklodowska-Curie Actions

OpenAlex ID: W4416724317