제목 : Pressure-induced metal-insulator transition in the Mott-insulating chalcogenide MnPS3
연사 : Heung-Sik Kim (Kangwon National University)
초록 : Van der Waals materials are exceptionally responsive to external stimuli. Press-induced layer sliding, metallicity, and superconductivity are fascinating examples. Inspired by opportunities in this area, we combined high pressure optical spectroscopies and first-principles calculations to reveal gap closure and metal-insulator transitions in MnPS3. Interestingly, dramatic color changes (green → yellow → red → black) take place as the charge gap shifts across the visible regime and into the near infrared, moving systematically toward closure at a rate of approximately -50 meV/Gpa and quenched only by the appearance of the insulator-metal transition. We further discuss the nature of the Mott-type metal-insulator transition, which likely involves collective layer sliding and breaking of P-dimer structure. This is an unique feature of this layered thiophosphate structure, qualitatively different from simple layered metal dichalcogenides. Our discovery suggests possible optoelectronic and memory applications of MnPS3 for the atomic-scale ultrathin devices.