Structural disorder in the quantum spin liquid candidate Na2BaCo(PO4)2

We seek to study low-temperature crystal structure of glaserite-type Na2BaCo(PO4)2 that was recently proposed as a candidate material for quantum spin liquid, an exotic state of matter with highly non-trivial electronic properties. The claim of the spin-liquid state realized in Na2BaCo(PO4)2 relies on the presence of an undistorted triangular geometry of the magnetic Co2+ ions. We surmise that this geometry may be in fact distorted as a result of cooperative rotations of the CoO6 octahedra and PO4 tetrahedra, and shall challenge this conjecture by high-resolution and total-scattering measurements at ID22. Our experiment will establish real structure of Na2BaCo(PO4)2 at low temperatures, shed light on the relevance of the spin-liquid scenario for this compound, and offer new insights into the structural chemistry of glaserite compounds.