Temperature and quantum anharmonic lattice effects on stability and superconductivity in lutetium trihydride

Abstract

In this work, we resolve conflicting experimental and theoretical findings related to the dynamical stability and superconducting properties of $Fm\overline{3}m$-LuH${}_3$, which was recently suggested as the parent phase harboring room-temperature superconductivity at near-ambient pressures. Including temperature and quantum anharmonic lattice effects in our calculations, we demonstrate that the theoretically predicted structural instability of the $Fm\overline{3}m$ phase near ambient pressures is suppressed for temperatures above $200\text{K}$. We provide a $p\,\unicode{x2013}\,T$ phase diagram for stability up to pressures of $6\text{GPa}$, where the required temperature for stability is reduced to $T>80\text{K}$. We also determine the superconducting critical temperature $T_{\text{c}}$ of $Fm\overline{3}m$-LuH${}_3$ within the Migdal-Eliashberg formalism, using temperature- and quantum-anharmonically-corrected phonon dispersions, finding that the expected $T_{\text{c}}$ for electron-phonon mediated superconductivity is in the range of $50$ $\unicode{x2013}$ $60\text{K}$, i.e., well below the temperatures required to stabilize the lattice. When considering moderate doping based on rigidly shifting the Fermi level, $T_{\text{c}}$ decreases for both hole and electron doping. Our results thus provide evidence that any observed room-temperature superconductivity in pure or doped $Fm\overline{3}m$-LuH${}_3$, if confirmed, cannot be explained by a conventional electron-phonon mediated pairing mechanism.

9 pages, 5 figures. Revised manuscript. Supplemental Information available on the journal website (open access)

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Cited by in corpus (13)

• Search for ambient superconductivity in the Lu-N-H system
• Observation of non-superconducting phase changes in LuH${}_{2\pm \text{x}}$N${}_y$
• Full-bandwidth anisotropic Migdal-Eliashberg theory and its application to superhydrides
• Assessing the feasibility of near-ambient conditions superconductivity in the Lu-N-H system
• Microscopic theory of colour in lutetium hydride
• IsoME: Streamlining High-Precision Eliashberg Calculations
• Novel Electronic Structure of Nitrogen-Doped Lutetium Hydrides
• Ab initio modeling of superconducting alloys
• Stability-superconductivity map for compressed Na-intercalated graphite
• Unveiling a Novel Metal-to-Metal Transition in LuH2: Critically Challenging Superconductivity Claims in Lutetium Hydrides
• Vacancy-free cubic superconducting NbN enabled by quantum anharmonicity
• Evidence of Molecular Hydrogen in the N-doped LuH3 System: a Possible Path to Superconductivity?
• High-$T_{\mathrm{c}}$ Ag${}_x$BC and Cu${}_x$BC superconductors accessible via topochemical reactions