Infrared and Raman spectroscopy study of Co-based honeycomb Na₂Co₂TeO₆

Layered honeycomb magnets have received lots of attention as potential candidates to realize Kitaev physics.  Current studies focus on 4d- or 5d-transition-metal honeycomb compounds for strong spin-orbit coupling. Recently, theoretical calculations propose that Kitaev interactions can also be realized in honeycomb magnets from 3d-transition-metal compounds [1,2]. Among them, Co-based honeycomb Na₂Co₂TeO₆ (NCTO) is antiferromagnetic ordered below T_N = 25K. More recent experimental studies on NCTO suggest that below T_N, magnetic field can suppress the long-range AFM order, and induce a disordered state in the field range of 7.5T < B < 10.5T before a field polarized state. Here we report the low-frequency infrared and Raman spectroscopy study on NCTO at low temperature and under high magnetic field up to 14T. A rich structure of magnetic excitations is observed across the AFM, disordered and polarized stats. The measurement results will be further discussed with theoretical calculations.

[1] Liu et. al., Phys. Rev. B 97, 014407 (2018)

[2] Liu et. al., Phys. Rev. Lett. 125, 047201 (2020)