UPS study of NiPS3 and FePS3 crystals using synchrotron radiation Original Research Article

Ultraviolet photoemission spectroscopy (UPS) has been applied to the investigation of the valence band structures of nickel and iron trisulfo-phosphates (NiPS3 and FePS3) using synchrotron radiation. The careful observation of UPS spectra gives the accurate binding energy associated with each spectral features. The UPS spectral structures of NiPS3 and FePS3 change their intensities strongly with varying incident photon energy. The constant initial state spectroscopy, in conjunction with the photon energy dependence of the UPS spectra, provides the assignment of every UPS spectral feature. These results reveal that the electronic structures of NiPS3 and FePS3 differ from each other, suggesting an explanation for the difference in the electric properties of these compounds.