Cs2Fe2(MoO4)3A Strongly Frustrated Magnet with Orbital Degrees of Freedom and Magnetocaloric Properties

• Published in: Chemistry of materials Vol. 36; no. 14; pp. 7016 - 7025
• Main Authors: Kubíčková, Lenka, Weber, Anna Katharina, Panthöfer, Martin, Calder, Stuart, Möller, Angela
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02-07-2024; American Chemical Society (ACS)
• Subjects: chemical calculations; chemical structure; energy; lattices; magnetic properties
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.4c01262

We report an in-depth study of the thermodynamic and magnetocaloric properties of a strongly frustrated magnet, Cs2Fe2(MoO4)3. The underlying structure belongs to the double trillium lattice, which consists of two FeII (S = 2) sites with easy-axis and easy-plane single-ion anisotropy. Detailed 57Fe Mössbauer spectroscopic investigations along with ligand-field calculations support the existence of disparate ground states. The antiferromagnetic ordered structure is presented by the propagation vector k = (0,0,0) with noncollinear magnetic moments of 2.97 μB (Fe1) and 0.17 μB (Fe2), respectively. Strong and disordered magnetic correlations exist in the temperature regime between T N ≈ 1.0 K and |θCW| ≈ 22 K. The large degeneracy of the ground state is investigated in terms of its magnetocaloric response. Magnetization and specific heat measurements indicate a significant magnetocaloric cooling efficiency, making this rare-earth-free compound a promising candidate for cryogenic magnetic refrigeration applications, with refrigeration capacity of 79 J kg–1 for Δ­(μ0 H) = 8 T.