Neutron Scattering Study of the Kitaev Spin-Liquid Candidate Material BaCo₂(AsO₄)₂

Recently, a new generation of Kitaev materials has been proposed that is based on the low spin configuration 3d⁷ Co²⁺. We present an inelastic single-crystal neutron scattering study of one such spin-liquid candidate material BaCo₂(AsO₄)₂ (BCAO). This material has attracted interest due to the observation of the suppression of magnetic order into a paragagnet-like phase above an in-plane critical field of H_ab≈0.55 T. This melting of order with field is reminiscent of α-RuCl₃, where the high field state is proposed to be a quantum spin-liquid.  Structural considerations and the small critical field make BCAO an appealing Kitaev spin-liquid candidate. The observed magnetic excitations in a fully field-polarized phase are modeled using linear spin-wave theory, and accompanying bulk characterization studies are used to determine the exchange interactions and place the material within the generalized phase diagram of the K-Γ-Γ'-J model.