Geometrical frustration versus Kitaev interactions in BaCo2(AsO4)2

• Published in: Proceedings of the National Academy of Sciences - PNAS 2023-01, Vol.120 (2), p.1
• Main Authors: Halloran, Thomas, Desrochers, Félix, Zhang, Emily Z, Chen, Tong, Chern, Li Ern, Xu, Zhijun, Winn, Barry, Graves-Brook, M, Stone, M B, Kolesnikov, Alexander I, Qiu, Yiming, Zhong, Ruidan, Cava, Robert, Kim, Yong Baek, Broholm, Collin
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Cobalt; Inelastic scattering; Liquid phases; Magnetic fields; Magnets; Magnons; Materials selection; Neutron scattering; Physical Sciences; Spin liquid; Spin structure; Structure factor
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2215509119

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 JKΓΓ′ model and the XXZ-J1-J3 model. We show that the existing experimental data can be consistently accounted for by the XXZ-J1-J3 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.