Laboratoire de Physique Théorique
Toulouse - UMR 5152

What we colloquially know about frustration, is that it prevents magnetic order. But the interesting part is not so much the absence of something, but rather what happens in its place.

Frustration usually stems from one of only two elementary units of spins : either triangles or tetrahedra. In this seminar we will explore an alternative route for frustration via molecular design in the metal-azolate framework [Mn(ta)2], whose units are centred tetrahedra made of five spins [1]. Using a combination of experiments, simulations and field theory, we will show that this material is proximate to a spin liquid that possesses one of the largest phase-space manifold known in the literature, even more degenerate than canonical models on the pyrochlore and kagome lattices. In addition, it is described by an emergent Coulomb gauge field theory coupled to charges, that can be seen as a "three-dimensional slab" of a four-dimensional structure [1,2]. In that sense, the description of this spin liquid is reminiscent of quasi-crystals, that are better understood in D+1 dimensions. Finally, we will explain how it evolves in presence of perturbations such as further neighbour couplings [1,2].

By varying the ligand and nature of the magnetic ion, we are convinced that metal-organic frameworks unlock a new door in frustrated magnetism beyond the standard kagome and pyrochlore structures.

[1] Nutakki, Röß-Ohlenroth, Volkmer, Jesche, Krug von Nidda, Tsirlin, Gegenwart, Pollet & Jaubert, Physical Review Research 5, L022018 (2023)

[2] Nutakki, Pollet & Jaubert, SciPost 15, 040 (2023)