Anatomy of the Band Structure of the Newest Apparent Near-Ambient Superconductor LuH 3 – x N x

Recently it was claimed that nitrogen-doped lutetium hydride exhibited a near-ambient superconducting transition with a temperature of 294 K at a pressure of only 10 kbar, this pressure being several orders of magnitude lower than previously demonstrated for hydrides under pressure. In this paper, we investigate within DFT + U the electronic structure of both parent lutetium hydride LuH 3 and nitrogen doped lutetium hydride LuH 2.75 N 0.25 . We calculated corresponding bands, density of states and Fermi surfaces with and without spin-orbit coupling (SOC). It is shown that in the stoichiometric system the Lu-5 d states cross the Fermi level while the H- 1s states make almost no contribution at the Fermi level. However, with nitrogen doping, the N‑ 2p states enter the Fermi level in large quantities and bring together a significant contribution from the H‑ 1s states. The presence of N- 2p and H- 1s states at the Fermi level in a doped compound can facilitate the emergence of superconductivity. Surprisingly, SOC splits quite significantly (0.1–0.25 eV) nitrogen bands in LuH 2.75 N 0.25 just below the Fermi level. For instance, nitrogen doping almost doubles the value of DOS at the Fermi level. Simple BCS analysis shows that the nitrogen doping of LuH 3 can provide T_c more than 100 K and even increase it with further hole doping.