Emergent moments in a Hund's impurity

TL;DR

This paper investigates a multiorbital Kondo impurity with Hund's interaction, revealing the emergence of large moments and their influence on the system's properties across a wide temperature range, relevant to Hund's metals.

Contribution

It introduces a dynamical large-N approach that efficiently captures the physics of Hund's coupled multiorbital impurities, including emergent moments and intermediate temperature phases.

Findings

Emergence of large magnetic moments in the impurity system

Identification of an intermediate paramagnetic phase due to emergent moments

Method enables analysis over many decades of temperature

Abstract

Motivated by the relevance of Hund's coupling in the context of multiorbital superconductors, we revisit the problem of a multiorbital Kondo impurity with Hund's interaction. Using dynamical large-N techniques, we propose an efficient approach that retains the essential physics at play, while providing a pathway to scalable quantum impurity solvers. We are able to follow the ground state, dynamic, and thermodynamic properties of this system over many decades of temperature. Our approach captures the emergence of large moments, and follows the stretched evolution of the physics down to their exponentially suppressed Kondo temperature. We focus our analysis on the intermediate finite temperature phase which presents an alternate paramagnetic state due to the emergent moment, and discuss the relevance of this regime to Hund's metals.