Optical magneto-spectroscopy methods (Raman scattering, far-infrared transmission, and photoluminescence) have been applied to investigate the properties of the ${\mathrm{NiPS}}_3$ semiconducting antiferromagnet. The fundamental magnon gap excitation in this van der Waals material has been found to be split into two components, in support of the biaxial character of the ${\mathrm{NiPS}}_3$ antiferromagnet. Photoluminescence measurements in the near-infrared spectral range show that the intriguing 1.475 eV excitation unique to the ${\mathrm{NiPS}}_3$ antiferromagnetic phase splits upon the application of the in-plane magnetic field. The observed splitting patterns are correlated with properties of magnon excitations and reproduced with the simple model proposed. Possible routes towards a firm identification of the spin-entangled 1.475 eV optical excitation in ${\mathrm{NiPS}}_3$, which can hardly be recognized as a coherent Zhang-Rice exciton, are discussed.

• Received 2 April 2023
• Revised 4 July 2023
• Accepted 11 September 2023

DOI:https://doi.org/10.1103/PhysRevB.108.115149