Quantum criticality in two dimensions and Marginal Fermi Liquid

TL;DR

This paper investigates the properties of a two-dimensional fermion system near a quantum critical point, proposing that inhomogeneities in spin excitations can explain the Marginal Fermi Liquid behavior observed in cuprates.

Contribution

It introduces a model with intrinsic inhomogeneities in spin excitations to explain Marginal Fermi Liquid phenomena in high-temperature superconductors.

Findings

Inhomogeneities suppress spatial correlations of antiferromagnetic excitations.

The model reproduces linear temperature dependence of resistivity.

Comparison with experimental data supports the doping dependence of resistivity slope.

Abstract

Kinetic properties of a two dimensional model of fermions interacting with antiferromagnetic spin excitations near the quantum critical point (QCP) are considered. The temperature or doping are assumed to be sufficiently high, such that the pseudogap does not appear. In contrast to standard spin-fermion models, it is assumed that there are intrinsic inhomogeneities in the system suppressing space correlations of the antiferromagnetic excitations. It is argued that the inhomogeneities in the spin excitations in the "strange metal" phase can be a consequence of existence of $\pi $-shifted domain walls in the doped antiferromagnetic phase. Averaging over the inhomogeneities and calculating physical quantities like resistivity and some others one can explain unusual properties of cuprates unified under the name "Marginal Fermi Liquid" (MFL). The dependence of the slope of the linear temperature dependence of the resistivity on doping is compared with experimental data.