Magnon gap excitations and spin-entangled optical transition in the van der Waals antiferromagnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>NiPS</mml:mtext><mml:mn>3</mml:mn></mml:msub></mml:math>
Dipankar Jana, Piotr Kapuściński, I. Mohelsky, Diana Václavková, Ivan Breslavetz, M. Orlita, C. Faugeras, M. Potemski
Abstract
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.