Geometrical frustration versus Kitaev interactions in BaCo2(AsO4)2

Recently, Co-based honeycomb magnets have been proposed as promising candidate materials to host the Kitaev spin liquid (KSL) state. One of the front-runners is BaCo2(AsO4)2 (BCAO), where it was suggested that the exchange processes between Co2+ ions via the surrounding edge-sharing oxygen octahedra could give rise to bond -dependent Kitaev interactions. In this work, we present and analyze a comprehensive inelastic neutron scattering (INS) study of BCAO with fields in the honeycomb plane. Combining the constraints from the magnon excitations in the high-field polarized state and the inelastic spin structure factor measured in zero magnetic field, we examine two leading theoretical models: the Kitaev-type JKFF' model and the XXZ-J1-J3model. We show that the existing experimental data can be consistently accounted for by the XXZ-J1-J3model but not by the JKF F' model, and we discuss the implications of these results for the realization of a spin liquid phase in BCAO and more generally for the realization of the Kitaev model in cobaltates.

Automated summary

Recently, Co-based honeycomb magnets have been proposed as promising candidate materials for Kitaev spin liquid. This study presents and analyzes an inelastic neutron scattering (INS) study of BaCo2(AsO4)2 (BCAO) with fields in the honeycomb plane. The results suggest that the XXZ-J1-J3 model, rather than the JKF F' model, can account for the experimental data consistently.