Ab initio study of the structural, vibrational and optical properties of potential parent structures of nitrogen-doped lutetium hydride

Abstract

The recent report of near-ambient conditions superconductivity in a nitrogen-doped lutetium hydride has inspired a large number of experimental studies with contradictory results. We model from first principles the physical properties of the possible parent structures of the reported superconductor, LuH${}_2$ and LuH${}_3$. We show that only the phonon band structure of LuH${}_3$ can explain the reported Raman spectra due to the presence of hydrogens at the interstitial octahedral sites. However, this structure is stabilized by anharmonicity only above 6 GPa. We find that the intriguing color change with pressure in the reported superconductor is consistent with the optical properties of LuH${}_2$, which are determined by the presence of an undamped interband plasmon. The plasmon blue-shifts with pressure and modifies the color of the sample without requiring any structural phase transition. Our findings suggest that the main component in the experiments is LuH${}_2$ with some extra hydrogen atoms at octahedral sites. None of LuH${}_2$ and LuH${}_3$ superconduct at high temperatures.

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Cited by in corpus (8)

• Observation of non-superconducting phase changes in LuH${}_{2\pm \text{x}}$N${}_y$
• Temperature and quantum anharmonic lattice effects on stability and superconductivity in lutetium trihydride
• Assessing the feasibility of near-ambient conditions superconductivity in the Lu-N-H system
• Anatomy of the band structure of the newest apparent near-ambient superconductor LuH${}_{3-x}$N${}_x$
• Unveiling a Novel Metal-to-Metal Transition in LuH2: Critically Challenging Superconductivity Claims in Lutetium Hydrides
• Evidence of Molecular Hydrogen in the N-doped LuH3 System: a Possible Path to Superconductivity?
• Superconductivity in barium hydrides via incorporation of light elements
• Ternary Phase Diagram of Nitrogen Doped Lutetium Hydrides