High-field terahertz spin excitations in the honeycomb magnet K₂Co₂TeO₆

We present a comprehensive terahertz spectroscopic investigation of the honeycomb magnet K₂Co₂TeO₆. Spin excitations are resolved and studied as a function of temperature, applied in-plane magnetic field up to 17T, as well as the polarization of the terahertz electromagnetic wave. The observed spin excitations are characterized by an evident field dependence, magnetic anisotropies and large Landé g-factors, which indicate important spin-orbit coupling and magnon-magnon interactions. The observed anisotropy suggests a possibly crucial role of Kitaev-type exchange interactions in K₂Co₂TeO₆. We will discuss our results also in comparison with thermodynamic measurements.