Geometric frustration inhibits magnetic systems from ordering, opening a window to unconventional phases of matter. The paradigmatic frustrated lattice in three dimensions to host a spin liquid is the pyrochlore, although there remain few experimental compounds thought to realize such a state. Here we go beyond the pyrochlore via molecular design in the metal-azolate framework [Mn(II)(ta)2], which realizes a closely related centred pyrochlore lattice of Mn-spins with S=5/2. Despite a Curie-Weiss temperature of −21 K indicating the energy scale of magnetic interactions, [Mn(II)(ta)2] orders at only 430 mK, putting it firmly in the category of highly frustrated magnets. Comparing magnetization and specific heat measurements to numerical results for a minimal Heisenberg model, we predict that this material displays distinct features of a classical spin liquid with a structure factor reflecting Coulomb physics in the presence of charges.
@article{arxiv.2203.08780,
title = {Frustration on a centred pyrochlore lattice in metal-organic frameworks},
author = {Rajah Nutakki and Richard Röß-Ohlenroth and Dirk Volkmer and Anton Jesche and Hans-Albrecht Krug von Nidda and Alexander A. Tsirlin and Philipp Gegenwart and Lode Pollet and Ludovic D. C. Jaubert},
journal= {arXiv preprint arXiv:2203.08780},
year = {2023}
}