Find a material with a continuous Neel to valence-bond-solid transition
In plain words
Deconfined criticality has been seen mostly in computer models. The goal is a real magnet where the change from magnetic order to a pattern of spin singlets happens continuously or nearly so.
Precise statement
Identify a quasi-2D $S = 1/2$ magnet tunable by pressure, field or chemistry through a Neel to VBS (or plaquette) transition, and determine whether the transition is continuous with measured exponents or first order with a measured order-parameter jump. Candidates include SrCu2(BO3)2 under pressure and field. An answer is the material with the measured character of the transition.
What would settle it
Neutron diffraction and NMR across the transition under pressure resolving both order parameters and any coexistence region.
Status in the literature
Cui et al. (Science 2023) reported a proximate deconfined critical point in SrCu2(BO3)2 with a weakly first-order transition.