The $s^\pm$-Wave Superconductivity in the Pressurized La$_4$Ni$_3$O$_{10}$

TL;DR

This study investigates the pairing mechanism and symmetry in pressurized La$_4$Ni$_3$O$_{10}$, proposing an $s^{}$-wave pairing driven by Fermi surface nesting and interlayer orbital interactions, supported by a six-orbital tight-binding model and RPA calculations.

Contribution

The paper introduces a detailed six-orbital model and identifies $s^{}$-wave pairing as the mechanism in La$_4$Ni$_3$O$_{10}$, highlighting the role of the non-bonding $d_{z^2}$ band and Fermi surface nesting.

Findings

Identification of $s^{}$-wave pairing symmetry.

Fermi surface nesting between specific pockets drives pairing.

Interlayer $d_{z^2}$ orbital pairing is dominant.

Abstract

Recently, evidence of superconductivity (SC) has been reported in pressurized La$_4$Ni$_3$O$_{10}$. Here we study the possible pairing mechanism and pairing symmetry in this material. Through fitting the density-functional-theory band structure, we provide a six-orbital tight-binding model. In comparison with the band structure of La$_3$Ni$_2$O$_7$, the additional non-bonding $d_{z^2}$ band is importance to the pairing mechanism here. When the multi-orbital Hubbard interactions are included, our random-phase-approximation based study yields an $s^{\pm}$-wave pairing. The dominant FS nesting with nesting vector $\mathbf{Q}_1\approx (\pi,\pi)$ is between the $\gamma$-pocket contributed by the bonding $d_{z^2}$ band top and the $\alpha_1$-pocket contributed by the non-bonding $d_{z^2}$ band bottom, leading to the strongest pairing gap amplitude and opposite gap signs within the two regimes. The dominant real-space pairing is the interlayer pairing between the $d_{z^2}$ orbitals. We have also studied the doping dependence of the pairing symmetry and $T_c$.