The recent report by Dasenbrock-Gammon et al. on the near-ambient superconductivity in N-doped lutetium hydride (Lu-N-H) [Nature 615, 244–250 (2023)] has gained much attention due to its enormous promise in applications. Our ab initio study on the potential parent phases suggests that the Raman spectra can be explained by the phonon dispersions of Fm-3m LuH₃, but this phase can only be stabilized by anharmonicity above 6 GPa and 300 K. Furthermore, the observed color change with pressure in the experiment is consistent with the optical properties of Fm-3m LuH₂ [1]. However, neither  LuH₃ nor LuH₂ exhibit superconductivity at 1 GPa.

To find a possible clue of near-ambient superconductivity, we performed high-throughput DFT screening of more than 15,000 variations of LuH₂ and LuH₃ with and without the involvement of N at 1 GPa [2]. However, N atoms exhibit a strong inclination towards covalent bonding with H, and lead to favoring insulating behavior rather than metallic properties. None high-temperature superconducting compounds are found. Despite the absence of room-temperature superconductivity at 1 GPa, we find that cubic Lu₄H₁₁N exhibits a high Tc of 100 K at 20 GPa, a large increase compared to 30 K in its parent LuH₃ at the same pressure. In addition, the LuH₁₀ and LuH₆ become high-temperature superconductors at 175 GPa and 100 GPa, with Tc of 286 K and 246 K, respectively. The strong quantum anharmonic and ionic effects are found to enable the dynamical stability and the high Tc in the three lutetium hydrides.

While high-temperature superconductivity is predicted to be unattainable in Lu-based hydrides at 1 GPa, we performed a machine learning search of more than 1 million compounds and predicted a series of ambient-pressure high-temperature superconducting hydrides [3]. Our further high-throughput ab initio electron-phonon coupling study finds around 50 superconducting hydrides with a critical temperature above 20 K. In particular, a family of compounds with composition Mg₂XH₆ where X=Rh, Ir, Pd, or Pt exhibit superconductivity in the range of 45-80 K and are (nearly) thermodynamically stable,  or even above 100K with appropriate electron doping of the Pt compound [4].

[1] Ð. Dangi ́c, P. Garcia-Goiricelaya, Y.-W. Fang, et al., Phys. Rev. B 108, 064517 (2023).
[2] Y.-W. Fang*, Ð. Dangi ́c*, and Ion Errea*, arXiv:2307.10699, (2023)
[3] T. F. T. Cerqueira, Y.-W. Fang, I. Errea, et al., to be submitted
[4] A. Sanna, T. F. T. Cerqueira, Y.-W. Fang, et al., npj Computational Materials accepted, (2024); [arXiv:2310.06804 (2023)]
 

superconducting hydride,pressure,electron-phonon coupling,quantum effect,ab initio study