Speaker
Description
Bilayer nickelate La$_3$Ni$_2$O$_7$ offers a new setting to study the interplay between Mottness, multi-orbital physics, and superconductivity. We show that a bilayer Hubbard model supports a molecular Mott state driven by strong interaction and interlayer coupling, which becomes self-doped through charge transfer to higher-energy bands as the interlayer coupling is reduced. Guided by this picture, we study a two-band $t$-$J$ model and find an orbital-selective $d$-wave superconducting state emerging only from the itinerant orbital, while the quasi-localized orbital suppresses pairing by promoting local inter-orbital bound states. These results support a picture of La$_3$Ni$_2$O$_7$ as a self-doped molecular Mott system and suggest that suppressing localized $d{z^2}$-derived states may help enhance superconductivity.