paper

Strong-coupling study of the pairing mechanism in pressurized LaNiO

arXiv:2504.12127 · doi:10.1103/f6sr-t6js

Abstract

Recently, the bilayer perovskite nickelate LaNiO has been reported to exhibit high-temperature superconductivity near K under a moderate pressure of about GPa. To investigate the underlying pairing mechanism and symmetry in this complex system, we propose and analyze a mixed spin- and spin- bilayer - model in the strong coupling regime. This model explicitly incorporates the crucial role of strong Hund's coupling, which favors the formation of local spin-triplet states from the two onsite orbital electrons at half-filling. We further investigate the model using both slave-particle mean-field theory and the density matrix renormalization group method. Our simulation results reveal that the dominate pairing channel is the interlayer one in the orbital. The Hund's coupling is shown to enhance superconductivity within a reasonable physical range. Moreover, electron doping strengthens superconductivity by increasing carrier density; in contrast, hole doping weakens superconductivity. These findings offer critical insights into the unconventional superconductivity of pressurized LaNiO and underline the important role of orbital-selective behavior and Hund's rule.

18 pages, 16 figures

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