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.
Highlights
Flat-band systems represent one of the paradigmatic systems to engineer correlated matter [1,2,3,4,5,6]
We demonstrate that the full phenomenology can be captured by symmetry broken mean-field method and compare these results with two genuine manybody methods, dynamical mean-field theory (DMFT) and tensor networks states
We have addressed the physics of a Kondo lattice problem, in which a conventional dispersive electron gas is replaced by a flat-band electronic state
Summary
Flat-band systems represent one of the paradigmatic systems to engineer correlated matter [1,2,3,4,5,6]. Quantum engineering has provided a variety of platforms potentially combining both flat bands and interactions, including atomic lattices [7,8,9,10], cold atoms [11,12,13], and twisted moire materials [14,15,16] Their potential for correlated physics stems from the vanishing electronic dispersion, which creates a greatly enhanced density of states at the Fermi energy [3,17,18,19]. The interaction between a local magnetic impurity and the conduction bath is determined by the Kondo temperature, increasing with the density of states, and divergent in the flat-band regime.
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