Resonant two-magnon Raman scattering at high pressures in the layered antiferromagnetic NiPS3

We have measured the Raman spectra of NiPS3 for pressures up to 27 Cpa at 1 20 K and room temperature using various lines from an argon ion laser. NiPS 3, is an S = 1, insulating, two-dimensional antiferromagnet which shows an anomalously broad two-magnon excitation. At high pressures, we observe a st rong dependence of the intensity, line shape, and frequency of the magnetic spectrum as a function of laser wavelength, reflecting pressure tuning of electronic transitions. NiPS3 is the only material exhibiting resonant two- magnon scattering other than the parent compounds of the cuprate supercondu ctors. [S0163-1829(99)06009-9].