Correlation-driven enhancement of pairing in a nematic Hund's metal

TL;DR

This paper explores how Hund-driven correlations influence superconductivity and nematicity in multiorbital systems, revealing that dynamical correlations are crucial for understanding pairing robustness and gap structures.

Contribution

It demonstrates that dynamical correlation effects beyond quasiparticle descriptions are vital for capturing superconductivity in nematic Hund metals, highlighting orbital-dependent gap formation.

Findings

Hund correlations enhance orbital differentiation of gaps

Nematic phase suppresses orbital polarization collapse

Different frequency windows contribute unevenly to pairing

Abstract

Superconductivity and nematicity coexist in the phase diagram of many correlated systems, including iron-based superconductors. We investigate how Hund-driven correlations reshape boson-mediated superconductivity in a multiorbital nematic metal. We find that dynamical correlation effects beyond a quasiparticle-only description are essential to capture the robustness of superconductivity in the Hund regime. In the nematic phase, Hund correlations simultaneously enhance the orbital differentiation of the superconducting gaps and inhibit the most extreme nematic-driven orbital polarization and coherence collapse that would otherwise suppress pairing at strong coupling. A controlled cutoff analysis reveals a nontrivial, orbital-dependent buildup of the gaps, indicating that different frequency windows of the correlated spectrum contribute unevenly to pairing in the nematic Hund regime. This implies that pairing mechanisms with different characteristic boson energies can lead to distinct gap structures and trends.