Disorder in Quantum Spin Liquid Candidates

Phys. Rev. B 101, 020406 (R) (2020)

I have recently led an effort to interpret and model the experimental data on single crystals of an insulator Ba₅CuIr₃O₁₂, that has previously been shown to exhibit highly frustrated magnetism of quasi-1D Cu-Ir trimer chains (see figure). Within the phenomenological framework I developed, all of the thermodynamic data (susceptibility, magnetization, specific heat) could be accounted for. The data has been found to be described by a disorder-dominated random singlet state, ruling out other possibilities. In this regard, an intrinsic source of disorder (Cu/Ir intermixing) has been identified, explaining the observation of a random singlet state in single crystals.