• Haglund, Amanda V.
• Matsuoka, Takahiro
• Smith, Kevin
• Feng, Erxi
• Musfeldt, Janice
• Mandrus, David G.
• Harms, Nathan
• Clune, Amanda
• Smith, Jesse S.

Abstract

<jats:title>Abstract</jats:title><jats:p>van der Waals solids are ideal platforms for the discovery of new states of matter and emergent properties under external stimuli. Under pressure, complex chalcogenides like <jats:italic>M</jats:italic>PS<jats:sub>3</jats:sub> (<jats:italic>M</jats:italic> = Mn, Ni, Co, V) host sliding and structural transitions, insulator-to-metal transitions, the possibility of an orbitally-selective Mott state, piezochromism, and superconductivity. In this work, we bring together diamond anvil cell techniques, infrared and Raman scattering spectroscopies, and X-ray diffraction with a detailed symmetry analysis and first-principles calculations to uncover a series of high-pressure phases in NiPS<jats:sub>3</jats:sub>. Remarkably, we find five different states of matter between ambient conditions and 39 GPa—quite different than in the other <jats:italic>M</jats:italic>PS<jats:sub>3</jats:sub> materials. Even more strikingly, infrared spectroscopy and X-ray diffraction combined with a symmetry analysis reveal both metallicity and loss of the inversion center above ~23 GPa suggesting that NiPS<jats:sub>3</jats:sub> may be a polar metal with a <jats:italic>P</jats:italic>3<jats:italic>m</jats:italic>1 space group under these conditions and <jats:italic>P</jats:italic>1 symmetry under maximum compression. In addition to identifying a candidate polar metal ripe for further inquiry, we suggest that pressure may tune other complex chalcogenides into this elusive state.</jats:p>

Topics

• phase
• x-ray diffraction
• space group
• infrared spectroscopy
• superconductivity
• superconductivity