Electron-phonon superconductivity in monolayer NiH3 and hole-doped CuH3: Role of hybridization of transition metal eg and hydrogen 1s states

Abstract

Developing general design principles for two-dimensional (2D) high-Tc superconductors remains a central challenge because reduced dimensionality fundamentally reshapes chemical bonding and electron-phonon interactions. Here, we identify a hybridization-based design principle for 2D hydrides, namely, strong σ-type hybridization between H 1s and transition-metal eg states that leaves the corresponding antibonding states partially occupied at the Fermi level. Guided by this principle, we show that monolayer NiH3, consisting of an edge-sharing NiH6 octahedral network, is a phonon-mediated superconductor with a predicted Tc of 104 K. This high Tc arises from strong coupling between the partially occupied Ni eg−H 1s antibonding states near the Fermi level and Ni-dominated phonon modes. To demonstrate the generality of this principle, we further examine hole-doped CuH3 (0.1 hole/f.u.), which also exhibits superconductivity through the same hybridization mechanism, but with a reduced Tc of 30 K because the Cu eg−H 1s antibonding states are more fully occupied and thus contribute less to the density of states at the Fermi level and to the electron-phonon coupling. Our results provide a feasible route to enhancing electron-phonon coupling in 2D hydrides and highlight hybridization engineering as a promising strategy for designing high-Tc superconductors.

Source-reported materials — not catalogue approval

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