The two faces of a magnetic honeycomb

H₃LiIr₂O₆ is a remarkable compound: it is the first iridium-based honeycomb magnet that does not become magnetically ordered at temperatures below a few kelvin. However, its overall behaviour and unusual thermodynamic properties indicate that it is governed by microscopic ingredients that differ substantially from those of Kitaev’s model. This is not a curse, but a blessing: understanding exotic magnetic phases is often achieved by studying related materials and models¹². Future experimental work in which, for example, large crystals of H₃LiIr₂O₆ are grown, or particles such as neutrons or photons are scattered off H₃LiIr₂O₆, could reveal whether the compound’s excitations have fractional quantum numbers — the ultimate experimental proof of a quantum spin liquid.

The soft-chemistry approach used by Kitagawa et al. offers great promise for controlling the properties of layered quantum magnets. However, with regard to oxide materials, there are challenges associated with the presence of chemical disorder and heterogeneities. For instance, the layered structure of H₃LiIr₂O₆ is prone to faults associated with the stacking of the layers¹³. In the future, it will be exciting to see chemists and physicists join forces to develop a deeper understanding of how material defects influence, and potentially even favour, entangled magnetic matter.