Spin excitations in a XY-type antiferromagnet NiPS₃

Magnons are collective spin excitations in magnetic crystals with long-range magnetic order. Magnons can be used to carry and transport information with low energy consumption and high speed. The recent popularly studied van der Waals (vdW) antiferromagnets with magnon in the terahertz range can be used as a good platform for ultrafast spintronics. Here, we performed magneto-Raman measurements on bulk NiPS₃ to detect its spin excitations including magnons. By polarization-resolved Raman measurement, we found two lower-energy magnon modes below 50 cm^-1, which is consistent with inelastic neutron scattering results and related theoretical calculations. The magnetic field dependence of these two magnon modes shows distinct behavior under the magnetic field applied along different crystal axes. Our results reveal the spin excitation in NiPS₃ and establish NiPS₃ as a desirable candidate for studying fundamental magnon physics.