Nagaoka supermetal in the particle-doped triangular Hubbard model

TL;DR

This paper introduces the Nagaoka supermetal, an interaction-driven quantum state in the doped triangular Hubbard model, characterized by anomalous transport and spectral properties linked to a Van Hove singularity.

Contribution

The study identifies and characterizes a new non-Fermi liquid state, the Nagaoka supermetal, arising from higher-order Van Hove singularities in a doped frustrated lattice.

Findings

DC resistivity shows sublinear temperature dependence.

Charge compressibility exhibits singular behavior.

Spectral weight at zero frequency is anomalous.

Abstract

While the interplay of correlations and geometric frustration in doped Mott insulators provides a fertile ground for exotic quantum phases, the nature of the metallic state emerging upon particle doping remains poorly understood. In this work, we investigate the triangular-lattice Hubbard model with particle doping and provide compelling evidence for an intrinsic, interaction-driven quantum state, which we term the Nagaoka supermetal. This state is characterized by a sublinear temperature dependence in the DC resistivity, along with singular behaviors in the charge compressibility and zero-frequency spectral weight. To understand the origin of these singular properties, we derive an effective low-energy model and demonstrate that a higher-order Van Hove singularity emerges from the reconstructed dispersion. This singularity gives rise to a power-law divergence in the density of states, capturing the anomalous properties observed in the supermetallic regime. Our findings offer a new perspective on non-Fermi liquid states in geometrically frustrated systems and are directly accessible in current ultracold atom experiments.