Geometrical frustration versus Kitaev interactions in BaCo<sub>2</sub>(AsO<sub>4</sub>)<sub>2</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 36608295.
- Also identified by DOI 10.1073/pnas.2215509119 and PMC identifier 9926200.
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Abstract
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 BaCo<sub>2</sub>(AsO<sub>4</sub>)<sub>2</sub> (BCAO), where it was suggested that the exchange processes between Co<sup>2+</sup> 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 [Formula: see text] model and the XXZ[Formula: see text]model. We show that the existing experimental data can be consistently accounted for by the XXZ[Formula: see text]model but not by the [Formula: see text] 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.