Fig. 4: Exciton polarization evolution and spin evolution probe in NiPS₃.

a Collection-polarization-dependent PL color map with applied fields along the a axis under different magnetic fields at 5 K. b Polar plots of the intensity of X- branch as a function of the collection polarization angle at selected magnitudes of the applied field. In each panel, the black dashed line represents the polar fitting without an external field. The polarization angle of the X- rotates with the increase of magnitude of the applied field. c PL polarization angle of X as a function of the in-plane magnetic field with different θ, compared with calculated PL polarization (labeled with solid curves) by φ_Cal-X = φ_L + 90°, where φ_L is the simulated Néel vector direction. The experimental polarization angles are the value after excluding the Faraday rotation effect. The experimental data of θ = 0^o is compared with calculated data of θ = 2^o. In the four configurations, the applied field direction is along 90^o, which is denoted by the black dashed line. Error bars represent standard errors from fitting function. d Simulated spin evolution under magnetic field with different magnitudes B and directions θ. The red and blue arrows represent the spin momenta M₁ and M₂, respectively.