Correlation-Driven Orbital-Selective Fermiology and Superconductivity in the Bilayer Nickelate La${}_3$Ni${}_2$O${}_7$

Abstract

Recent angle-resolved photoemission measurements on La${}_3$Ni${}_2$O${}_7$ have challenged the density-functional-theory-based picture of three Fermi surfaces by revealing that the $d_{z^2}$-derived ${\hat{I}}^3$ band can reside below the Fermi level. Motivated by this discrepancy, we investigate a realistic bilayer two-orbital Hubbard model using time-dependent variational principle (TDVP)-based cluster perturbation theory (CPT), alongside large-scale density matrix renormalization group (DMRG) calculations. Our TDVP-CPT calculations, performed on clusters of up to 16 physical sites, reveal that electronic correlations drive a pronounced orbital-selective reconstruction of the low-energy spectrum: the $d_{z^2}$ spectral weight is progressively depleted, the ${\hat{I}}^3$ band sinks below the Fermi level, and pseudogaps open on the remaining $\hat{I}\pm$ and ${\hat{I}}^2$ bands, leaving Fermi arcs dominated by the $d_{x^2-y^2}$ orbital at strong coupling. Furthermore, large-scale DMRG calculations demonstrate that the leading superconducting correlations evolve consistently with this Fermi surface reconstruction, transitioning from $d_{z^2}$-dominated to $d_{x^2-y^2}$-dominated interlayer spin-singlet pairing while retaining an $s_{\pm }$ structure. Consequently, our results indicate that the disappearance of the ${\hat{I}}^3$ pocket is not detrimental to superconductivity; rather, it signals a correlation-driven shift of the pairing channel mediated by interlayer antiferromagnetism, Hund's coupling, and inter-orbital hybridization.

7 pages, 4 figures for main text and 2 pages 4 figures for supplemental material