Mott Quantum Criticality in the Anisotropic 2D Hubbard Model

TL;DR

This paper provides evidence for Mott quantum criticality in an anisotropic 2D Hubbard model, showing how interchain hopping controls the metal-insulator transition and its critical behavior.

Contribution

The study demonstrates the existence of a quantum critical point in an anisotropic 2D Hubbard system using variational cluster and dynamical mean-field theories.

Findings

Critical end point $T_c$ approaches zero at $t_{ot}^c/t \\simeq 0.2

Fermi pocket volume vanishes continuously at the Mott transition below $t_{ot}^c$

First-order transition cuts off pocket volume reduction above $t_{ot}^c$

Abstract

We present evidence for Mott quantum criticality in an anisotropic two-dimensional system of coupled Hubbard chains at half-filling. In this scenario emerging from variational cluster approximation and cluster dynamical mean-field theory, the interchain hopping $t_{\perp}$ acts as a control parameter driving the second-order critical end point $T_c$ of the metal-insulator transition down to zero at $t_{\perp}^{c}/t\simeq 0.2$. Below $t_{\perp}^{c}$, the volume of the hole and electron Fermi pockets of a compensated metal vanishes continuously at the Mott transition. Above $t_{\perp}^{c}$, the volume reduction of the pockets is cut off by a first-order transition. We discuss the relevance of our findings to a putative quantum critical point in layered organic conductors, whose location remains elusive so far.