Hund's induced Fermi-liquid instabilities and enhanced quasiparticle interactions

TL;DR

This paper demonstrates that Hund's coupling can induce Fermi-liquid instabilities and enhance quasiparticle interactions in doped Mott insulators, potentially influencing superconductivity in Fe-based materials.

Contribution

It reveals how Hund's coupling promotes phase separation and quasiparticle scattering, providing new insights into Fermi-liquid behavior and superconductivity mechanisms.

Findings

Hund's coupling increases compressibility near the Hund's metal frontier.

Enhanced quasiparticle scattering may lead to symmetry breaking.

Simulations suggest relevance to high-temperature superconductivity.

Abstract

Hund's coupling is shown to generally favor, in a doped half-filled Mott insulator, an increase in the compressibility culminating in a Fermi-liquid instability towards phase separation. The largest effect is found about the frontier between an ordinary and an orbitally-decoupled ("Hund's") metal. The increased compressibility implies an enhancement of quasiparticle scattering, thus favoring other possible symmetry breakings. This physics is shown to happen in simulations of the 122 Fe-based superconductors, possibly implying the relevance of this mechanism in the enhancement of the the critical temperature for superconductivity.