Theory of magnetic short-range order for itinerant electron systems

TL;DR

This paper develops a self-consistent renormalization theory for magnetic short-range order in itinerant electron systems, using the Hubbard model and numerical evaluations at zero temperature, revealing phase behavior consistent with high-Tc cuprate experiments.

Contribution

It introduces a novel approach combining slave-boson and cluster variational methods to incorporate short-range order at the saddle-point level.

Findings

Suppression of magnetic long-range order in favor of paramagnetic phase with antiferromagnetic SRO

Increase in spin susceptibility with doping up to the transition point

Good agreement with experimental data on high-Tc cuprates

Abstract

On the basis of the one--band t-t'-Hubbard model a self-consistent renormalization theory of magnetic short--range order (SRO) in the paramagnetic phase is presented combining the four-field slave-boson functional-integral scheme with the cluster variational method. Contrary to previous SRO approaches the SRO is incorporated at the saddle-point and pair-approximation levels. A detailed numerical evaluation of the theory is performed at zero temperature, where both the hole- and electron-doped cases as well as band-structure effects are studied. The ground--state phase diagram shows the suppression of magnetic long-range order in favour of a paramagnetic phase with antiferromagnetic SRO in a wide doping region. In this phase the uniform static spin susceptibility increases upon doping up to the transition to the Pauli paraphase. Comparing the theory with experiments on high--T_c cuprates a good agreement is found.