Spin-Orbital Short-Range Order on a Honeycomb-Based Lattice

Frustrated systems, in which the geometry of the crystal lattice stands in the way of achieving an energetic minimum on all lattice sites simultaneously, have the potential to remain disordered down to the lowest temperatures. Numerous experimental efforts to find a material with a truly fluctuating ground state have failed because ordering often sets in at a finite temperature owing to symmetry breaking. Nakatsuji et al. (p. [559][1]; see the Perspective by [Balents][2] ) identify the compound Ba3CuSb2O9 as a promising candidate for this state; the Cu-Sb dipoles reside on a hexagonal structure, forming fluctuating spin singlets. Multiple lines of evidence suggest that the material does not order down to the millikelvin temperature range, remaining magnetically isotropic. [1]: /lookup/doi/10.1126/science.1212154 [2]: /lookup/doi/10.1126/science.1221364