Effects of different concentrations of topotactic hydrogen impurities on the electronic structure of nickelate superconductors

Abstract

Infinite-layer nickelate superconductors have recently been discovered to share both similarities and differences with cuprate superconductors. Notably, the incorporation of hydrogen (H) through topotactic reduction has been found to play a critical role in their electronic structure and, consequently, their superconductivity. In this study, we utilized a theoretical approach combining density-functional theory and impurity approximation to design three characteristic multi-orbital Hubbard models representing low, moderate, and high concentrations of topotactic-hydrogen. Consistent with experimental findings, our simulations revealed that both low and high concentrations of topotactic-hydrogen induce high-spin states (S=1) that are composed by holes at dx2−y2 and dz2 orbitals and consequently the emergent intersite hopping between dz2 to dx2−y2 is unfavorable for superconductivity. Conversely, an optimal concentration of 25% H aligns with the single Ni-dx2−y2 band picture of superconductivity in infinite-layer nickelates, demonstrating its beneficial effect on promoting superconducting behavior.

Source-reported materials — not catalogue approval

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