Unified intermediate coupling description of the pseudogap and the strange metal phases of cuprates

TL;DR

This paper demonstrates that an intermediate coupling one-band Hubbard model can effectively describe the pseudogap and strange metal phases in cuprates, challenging the notion that strong coupling is necessary.

Contribution

It introduces a simple postgaussian approximation for intermediate couplings to unify the description of pseudogap and strange metal phases in cuprates.

Findings

Linear resistivity with Planckian coefficient observed

Spectroscopic and transport properties are explained within the model

Intermediate coupling U/t=1.5-4 suffices for doping range p=0.1-0.3

Abstract

A one band Hubbard model with intermediate coupling is shown to describe the two most important unusual features of a normal state: linear resistivity strange metal and the pseudogap. Both the spectroscopic and transport properties of the cuprates are considered on the same footing by employing a relatively simple postgaussian approximation valid for the intermediate couplings $U/t=1.5-4$ in relevant temperatures $T>100{\rm K}.$ In the doping range $\ p=0.1-0.3$, the value of $U$ is smaller than that in the parent material. For a smaller doping, especially in the Mott insulator phase, the coupling is large compared to the effective tight binding scale and a different method is required. This scenario provides an alternative to the paradigm that the coupling should be strong, say $U/t>6$, in order to describe the strange metal. We argue that to obtain phenomenologically acceptable underdoped normal state characteristics like $T^{\ast }$, pseudogap values, and spectral weight distribution, a large value of $U$ is detrimental. Surprisingly the resistivity in the above temperature range is linear $\rho =\rho_{0}+\alpha \frac{m^{\ast }}{e^{2}n\hbar }T$ with the "Planckian" coefficient $\alpha $ of order one.