Kondo-lattice-mediated interactions in flat band systems

TL;DR

This paper investigates how Kondo lattice interactions influence flat band systems, revealing a magnetically ordered state due to underscreened regimes, thus linking flat band physics with Kondo many-body effects.

Contribution

It introduces flat band Kondo lattice models and demonstrates the emergence of magnetic order through advanced theoretical methods, a novel exploration in strongly correlated flat band systems.

Findings

Emergence of a magnetically ordered state in flat band Kondo lattices

Identification of a robust underscreened regime leading to magnetic order

Application of dynamical mean-field theory and tensor networks in this context

Abstract

Electronic flat bands represent a paradigmatic platform to realize strongly correlated matter due to their associated divergent density of states. In common instances, including electron-electron interactions leads to magnetic instabilities for repulsive interactions and superconductivity for attractive interactions. Nevertheless, interactions of Kondo nature in flat band systems have remained relatively unexplored. Here we address the emergence of interacting states mediated by Kondo lattice coupled to a flat band system. Combining dynamical mean-field theory and tensor networks methods to solve flat band Kondo lattice models in one and two dimensions, we show the emergence of a robust underscreened regime leading to a magnetically ordered state in the flat band. Our results put forward flat band Kondo lattice models as a platform to explore the genuine interplay between flat band physics and many-body Kondo screening.