Bad-metal behavior reveals Mott quantum criticality in doped Hubbard models

TL;DR

This paper links bad-metal behavior to Mott quantum criticality in doped Hubbard models, showing that the resistivity scaling and quantum critical region explain experimental observations of strong correlation effects.

Contribution

It demonstrates that Mott quantum criticality underpins bad-metal behavior in a fully frustrated Hubbard model, providing a quantitative framework for understanding resistivity near the MIR limit.

Findings

Resistivity exhibits quantum critical scaling across the bad-metal regime.

Mott quantum criticality dominates the phase diagram at low temperatures.

The results align with experimental observations of strongly correlated materials.

Abstract

Bad-Metal (BM) behavior featuring linear temperature dependence of the resistivity extending to well above the Mott-Ioffe-Regel (MIR) limit is often viewed as one of the key unresolved signatures of strong correlation. Here we associate the BM behavior with the Mott quantum criticality by examining a fully frustrated Hubbard model where all long-range magnetic orders are suppressed, and the Mott problem can be rigorously solved through Dynamical Mean-Field Theory. We show that for the doped Mott insulator regime, the coexistence dome and the associated first-order Mott metal-insulator transition are confined to extremely low temperatures, while clear signatures of Mott quantum criticality emerge across much of the phase diagram. Remarkable scaling behavior is identified for the entire family of resistivity curves, with a quantum critical region covering the entire BM regime, providing not only insight, but also quantitative understanding around the MIR limit, in agreement with the available experiments.