Magnetic Interactions in a Honeycomb Cobaltate are Not Explained by the Previously Proposed Kitaev Model

March 15, 2023
Magnetic Interactions in a Honeycomb Cobaltate are Not Explained by the Previously Proposed Kitaev M
Symmetrized neutron diffraction maps measured as a function of magnetic field indicating the evolution of the magnetic structure. The data is presented in three constant momentum transfer (Qperp) slices with Qperp integrated over the ranges indicated.

Scientific Achievement

The magnetic exchange constants in the honeycomb lattice material BaCo2(AsO4)2 are well described by the XXZ-J1-J3 model as opposed to the proposed behavior with bond-dependent Kitaev interactions.

Significance and Impact

The negligible bond-dependent interactions in BaCo2(AsO4)2 calls for careful reexamination of the proposal that honeycomb cobaltates may be promising candidates for Kitaev physics.

Research Details

  • The full magnetic excitation spectra were experimentally measured with in-plane magnetic fields and compared to detailed calculations of the excitation spectra in both the Kitaev and XXZ-J1-J3 models.
  • The results are not compatible with the proposed Kitaev interactions, and the two models of magnetism in BaCo2(AsO4)2 are successfully differentiated.

“Geometrical frustration versus Kitaev interactions in BaCo2(AsO4)2,”
homas Halloran, Félix Desrochers, Emily Z. Zhang, Tong Chen, Li Ern Chern, Zhijun Xu, Barry Winn, M. Graves-Brook, M. B. Stone, Alexander I. Kolesnikov, Yiming Qiu, Ruidan Zhong, Robert Cava, Yong Baek Kim and Collin Broholma,
Proceeding of the National Academies of Sciences 120, e2215509119 (2023). DOI: https://www.pnas.org/doi/abs/10.1073/pnas.2215509119