Find a material with a Kitaev spin-liquid ground state in zero field
In plain words
All known Kitaev candidates either order magnetically at low temperature or are too disordered to tell. The goal is a real crystal whose ground state without any applied field is the Kitaev spin liquid.
Precise statement
Identify a compound with bond-dependent Kitaev exchange $K$ dominant enough over Heisenberg $J$ and off-diagonal $\Gamma$ terms to lie inside the Kitaev phase of the $J-K-\Gamma$ model, showing no magnetic order or spin freezing down to $k_{\mathrm{B}} T << \mid K \mid$ and fractionalized excitations confirmed spectroscopically. Candidates include H3LiIr2O6 (no order but strong disorder) and cobalt-based honeycomb compounds (Na2Co2TeO6, BaCo2(AsO4)2), whose Kitaev fraction is disputed. An answer is the material with its measured exchange parameters.
What would settle it
A clean single crystal with exchange parameters inside the Kitaev phase, no order to the lowest temperature, and neutron and thermal-transport data consistent with Majorana and flux excitations.