Novel Electronic Structure of Nitrogen-Doped Lutetium Hydrides

Abstract

First-principles density functional theory (DFT) calculations of Lu-H-N compounds reveal low-energy configurations of Fm$\overline{3}$m Lu${}_8$H${}_{23-x}$N structures that exhibit novel electronic properties such as flat bands, sharply peaked densities of states (van Hove singularities, vHs), and intersecting Dirac cones near the Fermi energy (E${}_F$). These N-doped LuH${}_3$-based structures also exhibit an interconnected metallic hydrogen network, which is a common feature of high-T${}_c$ hydride superconductors. Electronic property systematics give estimates of T${}_c$ for optimally ordered structures that are well above the critical temperatures predicted for structures considered previously. The vHs and flat bands near E${}_F$ are enhanced in DFT+U calculations, implying strong correlation physics should also be considered for first-principles studies of these materials. These results provide a basis for understanding the novel electronic properties observed for nitrogen-doped lutetium hydride.

Submitted to PRL. 4 main figures, 15 SI Figures, 1 table. 5 pages (13 pgs SI)

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