Efficient slave-boson approach for multiorbital two-particle response functions and superconductivity

TL;DR

This paper introduces an efficient slave-boson method to compute two-particle response functions in multiorbital strongly correlated systems, revealing the mechanisms behind s-wave orbital antisymmetric spin-triplet superconductivity in Hund's metals.

Contribution

The authors develop a novel computational approach based on fluctuation around rotationally-invariant slave-boson saddle-point for multiorbital systems, enabling detailed analysis of pairing mechanisms.

Findings

Particle-particle channel drives pairing instability near Hund's metal crossover.

Particle-hole spin fluctuations induce s-wave pairing before Hund's regime.

Method facilitates investigation of pairing mechanisms in realistic correlated materials.

Abstract

We develop an efficient approach for computing two-particle response functions and interaction vertices for multiorbital strongly correlated systems based on fluctuation around rotationally-invariant slave-boson saddle-point. The method is applied to the degenerate three-orbital Hubbard-Kanamori model for investigating the origin of the s-wave orbital antisymmetric spin-triplet superconductivity in the Hund's metal regime, previously found in the dynamical mean-field theory studies. By computing the pairing interaction considering the particle-particle and the particle-hole scattering channels, we identify the mechanism leading to the pairing instability around Hund's metal crossover arises from the particle-particle channel, containing the local electron pair fluctuation between different particle-number sectors of the atomic Hilbert space. On the other hand, the particle-hole spin fluctuations induce the s-wave pairing instability before entering the Hund's regime. Our approach paves the way for investigating the pairing mechanism in realistic correlated materials.