Spin excitations underlying the 1/3 magnetization plateau phase of a spin-1 Kitaev honeycomb candidate

In our previous work, we unveiled an unprecedented robust 1/3 magnetization plateau phase in a genuine honeycomb lattice without geometrical frustration. By carrying out elastic neutron scattering measurement, we have pinned down the unusual partial-spin-flop magnetic structure responsible for the 1/3 plateau phase. By summarizing the magnetometry data and neutron results, we establish a magnetic phase diagram for Na3Ni2BiO6 (NNBO). Our results strongly suggest that the presence of bond-dependent Kitaev interactions in NNBO is very likely but spectroscopic evidence is still lacking. Although we have found the highly anisotropic spin waves in zero field consistent with the conjecture of the presence of the Kitaev interactions, little is known about the excitation spectra in plateau phase. Furthermore, applying a magnetic field that fully polarizes the system and studying the excitation spectra from which one can extract the exchange parameters is equally important. Therefore, high-field studies on the 1/3 plateau and fully polarized state in the magnet are urgently desired.