Entropy-stabilized materials as a platform to explore terbium-based pyrochlore frustrated magnets

• Published in: Communications materials Vol. 5; no. 1; pp. 162 - 10
• Main Authors: Vayer, Florianne, Petit, Sylvain, Damay, Françoise, Embs, Jan, Rols, Stéphane, Colin, Claire, Lhotel, Elsa, Bounoua, Dalila, Dragoe, Nita, Bérardan, David, Decorse, Claudia
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21.08.2024; Nature Publishing Group; Nature; Nature Portfolio
• Subjects: 639/301; 639/766; 639/766/119; Antiferromagnetism; Atomic properties; Chemistry and Materials Science; Entropy; Excitation spectra; Low temperature; Magnets; Materials Science; Oxygen atoms; Physics; Pyrochlores; Quadrupole interaction; Quadrupoles; Spin ice; Spin liquid
• ISSN: 2662-4443; 2662-4443
• DOI: 10.1038/s43246-024-00589-y

Two decades of work have shown that the physics of Tb-based pyrochlores is controlled by a subtle equilibrium between quadrupole-quadrupole and dipolar-dipolar magnetic interactions, as exemplified by the ordered spin ice Tb 2 Sn 2 O 7 and the quantum spin liquid candidate Tb 2 Ti 2 O 7 . The high-entropy approach is thus quite promising, as it offers the possibility of a delicate tuning of chemical disorder. In this work, we investigate the entropy-stabilized pyrochlore compound Tb 2 (TiZrHfGeSn) 2 O 7 . We report the lack of long range magnetic order, yet the observed magnetic diffuse scattering is characteristic of antiferromagnetic first-neighbor correlations. The crystal field excitation spectrum, with broaden levels, visibly reflects the smooth environmental disorder of the Tb environment. The low energy dynamics are characterized by a narrow mode at about 0.4 meV, consistent with specific heat. Remarkably, as illustrated by a model of random isotropic shifts of oxygen atoms around Tb ions, the spectral weight of this mode is a direct consequence of deviations from the D 3d symmetry at Tb sites. In the light of these results, quadrupolar interactions are also discussed. Frustrated magnetic systems such as pyrochlores are interesting for the complexity of their competing low-temperature phases. Here, the intrinsic disorder of the entropy-stabilized compound Tb 2 (TiZrHfGeSn) 2 O 7 is utilized to investigate the elusive ground state of Tb-based pyrochlore magnets.