Correlation-Driven Orbital-Selective Fermiology and Superconductivity in the Bilayer Nickelate La₃Ni₂O₇
Based on the bilayer two-orbital Hubbard model, this study systematically investigates the effects of electronic correlations on the Fermi surface topology and superconducting pairing symmetry in La₃Ni₂O₇ using the time-dependent variational principle cluster perturbation theory (TDVP-CPT) and large-scale density matrix renormalization group (DMRG) methods. TDVP-CPT calculations on clusters containing up to 16 physical sites reveal that electronic correlations drive significant orbital-selective low-energy spectral reconstruction: the spectral weight of the d_{z²} orbital is progressively depleted, the γ band sinks below the Fermi level, while the α and β bands exhibit a pseudogap, ultimately leading to the formation of a Fermi arc dominated by the d_{x²-y²} orbital in the strong-coupling regime. DMRG calculations further demonstrate that the dominant superconducting pairing correlations evolve consistently with this Fermi surface reconstruction, transitioning from interlayer spin singlet pairing mediated primarily by the d_{z²} orbital in the weak-coupling regime to pairing dominated by the d_{x²-y²} orbital in the strong-coupling regime, while maintaining s±-wave symmetry throughout. The study indicates that the disappearance of the γ Fermi surface does not suppress superconductivity but instead signifies a correlation-driven change in the pairing channel, with key intermediate mechanisms including interlayer antiferromagnetic fluctuations, Hund coupling, and interorbital hybridization.