"Complex chalcogenides under pressure"
Van der Waals solids are well known to host remarkable phase diagrams with competing phases, unusual energy transfer processes, and elusive states of matter. Among this class of materials, chalcogenides have emerged as the most flexible and relevant platforms for unraveling charge-structure-function relationships. Inspired by opportunities in his area, we combined high pressure spectroscopies with first-principles calculations to explore the properties of MnPS 3 and CrSiTe 3 under external stimuli. MnPS 3 displays dramatic color changes (green to yellow to red to black) as the charge gap shifts across the visible regime – an effect that is quenched by the appearance of the insulator-to-metal transition - whereas CrSiTe 3 hosts a pressure-induced structural transition that triggers the insulator-metal transition and a nexus of activity that hides a quantum critical point and allows superconductivity to emerge. In addition to uncovering intriguing and tunable functionality that is likely to appear in other complex chalcogenides, these effects revise our understanding of the interplay between charge, structure, and magnetism in layered materials and accelerate the development of technologies that take advantage of force-activated properties.
