Frustration on a centered pyrochlore lattice in metal-organic frameworks
Rajah P. Nutakki, Richard Röß‐Ohlenroth, Dirk Volkmer, Anton Jesche, Hans‐Albrecht Krug von Nidda, Alexander A. Tsirlin, P. Gegenwart, Lode Pollet, Ludovic D. C. Jaubert
Abstract
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.