Hidden Kondo lattice physics in single-orbital Hubbard models

TL;DR

This paper reveals how single-orbital Hubbard models can exhibit complex Kondo-lattice-like physics, including non-Fermi-liquid behavior and pseudo-gaps, through basis transformations that map them to effective multi-orbital systems.

Contribution

It introduces a method to map single-orbital Hubbard models to multi-orbital descriptions, explaining complex correlation phenomena and emergent Kondo-lattice-like behavior.

Findings

Mapping explains non-Fermi-liquid states in Hubbard models.

Identifies Kondo-lattice-like behavior in flat band systems.

Clarifies origin of pseudo-gaps in correlated metals.

Abstract

Single-orbital Hubbard models exhibit remarkably nontrivial correlation phenomena, even on nonfrustrated bipartite lattices. Some of these, like non-Fermi-liquid metal states, or the coexistence of heavy and light quasi-particles, are reminiscent of the properties of more complex multi-orbital or Kondo-lattice systems. Here, we use basis transformations to map single-orbital models to effective multi-orbital descriptions and clarify how a ferromagnetic Kondo-lattice-like behavior emerges in prototypical models with flat bands or van Hove singularities in the density of states: the Hubbard model on the diamond chain, square-lattice, Lieb lattice and honeycomb lattice. In particular, this mapping explains the non-Fermi-liquid states and pseudo-gaps found in the correlated metal regime.