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.
Highlights
Slave-boson approaches are among the most widely used theories for describing strongly correlated systems [1,2,3,4,5,6,7]
rotationally invariant slave-boson (RISB) has been reformulated as a quantum embedding theory, where the interacting lattice problem is mapped to an impurity problem coupled to a self-consistently determined environment [21], similar to dynamical mean-field theory (DMFT) and density matrix embedding theory (DMET) [8,23,24]
We apply our method to the degenerate threeorbital Hubbard-Kanamori model to investigate the origin of the s-wave orbital-antisymmetric spin-triplet pairing instability in Hund’s metal regime, previously found in the DMFT
Summary
Slave-boson approaches are among the most widely used theories for describing strongly correlated systems [1,2,3,4,5,6,7]. The development of the rotationally invariant slave-boson (RISB) saddle-point approximation [9], equivalent to the Gutzwiller approximation (GA) [10,11], has been extended to realistic multiorbital systems, in combination with density functional theory [12,13], uncovering many intriguing phenomena, including the selectiveMott transition [7,14,15], Hund’s metal behavior [16,17,18,19], valence fluctuations, and correlation induced topological materials [20,21,22]. The two methods, originally proposed for describing the ground state or low-temperature properties, have been extended to study the finite-temperature effects, the nonequilibrium dynamics, the excited states, and the single-particle spectral functions in correlated systems [27,28,29,30,31,32,33]
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