Geometrical frustration versus Kitaev interactions in BaCo<sub>2</sub>(AsO<sub>4</sub>)
ORAL
Abstract
Recently, Co-based honeycomb magnets have been proposed as promising candidate materials to host the Kitaev spin liquid 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 comprehensive inelastic neutron scattering studies 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 JKΓΓ' model and the XXZ-J1J3 model. We show that the existing experimental data can be consistently accounted for by the XXZ-J1J3 model but not by the JKΓΓ' 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.
*This work was supported as part of the Institute for Quantum Matter, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0019331. C.B. was supported by the Gordon and Betty Moore foundation EPIQS program under GBMF9456. F.D., E.Z.Z., and Y.B.K. were supported by the NSERC of Canada and the Center for Quantum Materials at the University of Toronto. E.Z.Z. was further supported by the NSERC Canada Graduate Scholarships-Doctoral (CGS-D). The research at the ORNL Spallation Neutron Source was sponsored by the U.S. Department of Energy, Office of Basic Energy Sciences. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Most of the computations were performed on the Cedar and Niagara clusters, which are hosted by WestGrid and SciNet in partnership with Compute Canada.
