Identifying magnetic excitations and crystal-field states in the honeycomb antiferromagnet Na₃Co₂SbO₆ using Raman magneto-spectroscopy

Honeycomb Co²⁺ compounds have recently been identified as promising candidates for the realization of the exactly-solvable Kitaev quantum spin liquid model [1]. However, virtually all of them establish a long-range magnetic order at low temperatures due to dominance of non-Kitaev interactions. One way to suppress the long-range order is by applying a magnetic field. In this regard, the 3d cobaltate Na₃Co₂SbO₆ (NCSO) is particularly promising as it has relatively low Neel temperature (T_N = ~5-8K) and small saturation fields (B* = ~1.9T) [2]. Here, we report on the low-temperature magneto-Raman investigation of single-crystal NCSO. In the polarized state, we identified low-energy magnons and extracted corresponding g-factors for different orientations of the in-plane magnetic field with respect to the crystal axes. The magnon energies and the field dispersion are well captured by linear spin wave theory. Futhermore, we observe low-lying crystal-field excitations in NCSO, which play an important role in the magnetic couplings between spin-orbit coupled Co moments.



[1] AL Sanders, et al. PRB 106, 014413 (2022)

[2] Z Hu, et al. PRB 109, 054411 (2024)