Fig. 3: Raman and infrared spectroscopy across the sliding and metal–insulator transitions in MnPS₃.

a Raman-active vibrational mode frequency vs. pressure across the sliding transition. The gray bar denotes the crossover range, and closed/open circles denote data from two different runs. b Infrared reflectance spectra at ambient conditions and in the metallic phase, depicting the appearance of a Drude. The dashed lines guide the eye—eliminating the diamond signature from the response. c Close up view of the P–S stretching mode, which is sharp and strong at ambient pressure and screened in the metallic state by the Drude.