Thermodynamics of a bad metal-Mott insulator transition in the presence of frustration

TL;DR

This study investigates the thermodynamic properties of the Hubbard model on an anisotropic triangular lattice, revealing characteristics of a bad metal-Mott insulator transition influenced by frustration.

Contribution

It provides a detailed numerical analysis of thermodynamic signatures of the transition and highlights the role of frustration in modifying spin excitations and correlations.

Findings

Identification of a metal-Mott insulator transition via charge susceptibility.

Characterization of the metallic phase as a bad metal with large entropy and spin susceptibility.

Frustration enhances low-lying spin excitations and reduces long-range spin correlations.

Abstract

We study a range of thermodynamic properties (charge susceptibility, specific heat, entropy and spin susceptibility) of the Hubbard model on the anisotropic triangular lattice at half filling by means of the numerical finite-temperature Lanczos method. We observe clear signatures of a metal-Mott insulator transition in the charge susceptibility, and show that the metallic phase is characterized by a small charge susceptibility, large entropy, low coherence temperature, large renormalized quasiparticle mass, and large spin susceptibility. We show that the local magnetic moment in the metallic phase is large and comparable to the local moment in the insulating phase. These are all characteristics of bad metallic behavior. In addition, we show how frustration increases the density of low-lying spin excitations in the Mott insulating phase and decreases longer range spin correlations.