Resonant two-magnon Raman scattering at high pressures in the layered antiferromagneticNiPS3

Abstract

We have measured the Raman spectra of ${\mathrm{NiPS}}_3$ for pressures up to 27 GPa at 120 K and room temperature using various lines from an argon ion laser. ${\mathrm{NiPS}}_3$ is an $S=1,$ insulating, two-dimensional antiferromagnet which shows an anomalously broad two-magnon excitation. At high pressures, we observe a strong dependence of the intensity, line shape, and frequency of the magnetic spectrum as a function of laser wavelength, reflecting pressure tuning of electronic transitions. ${\mathrm{NiPS}}_3$ is the only material exhibiting resonant two-magnon scattering other than the parent compounds of the cuprate superconductors.