Shifting superconducting dome of two-dimensional hole-doped Hubbard model by a dry Fermi sea: enhanced d-wave pairing in the overdoped regime

TL;DR

This study uses quantum Monte Carlo simulations to show that adding a dry Fermi sea to a 2D Hubbard model shifts the superconducting dome towards overdoped regimes, enhancing d-wave pairing.

Contribution

It reveals how an additional conduction band influences the superconducting properties and phase diagram of a correlated Hubbard layer, providing new insights into tuning superconductivity.

Findings

Superconducting dome shifts to higher doping with dry Fermi sea

Enhanced d-wave pairing in the overdoped regime

Pseudogap crossover line also shifts to higher doping

Abstract

Motivated by the presence of an extremely small electron pocket in the electronic band structure of infinite-layer (IL) nickelate superconductors, we systematically explore the superconducting (SC) properties of a two-dimensional Hubbard model influenced by an additional conduction band with small occupancy (dry Fermi sea). Our dynamic cluster quantum Monte Carlo calculations demonstrated the unusual impact of this additional dry metallic layer, which shifts the SC dome of the correlated Hubbard layer towards the overdoped regime, namely the $d$-wave SC can be enhanced (suppressed) in the overdoped (underdoped) regime. Simultaneously, the pseudogap (PG) crossover line shifts to the same higher doping regime as well. Our analysis revealed the interplay of the effective pairing interaction, pair-field susceptibility, and antiferromagnetic spin fluctuation in the underlying non-monotonic physics. We postulate on the physical picture of SC dome shift in terms of the Kondo-type electron-hole binding in the case of a dry additional conduction band. Our investigation provided valuable new insights on tuning the SC properties via external dry bands.