Finite-temperature properties of doped antiferromagnets

TL;DR

This paper reviews numerical studies of doped antiferromagnets using the finite-temperature Lanczos method, showing the t-J model captures key anomalous properties of cuprates and reveals universal behaviors at intermediate doping.

Contribution

It introduces a detailed numerical analysis of the t-J model at finite temperature, connecting theoretical results with experimental observations of cuprates.

Findings

The t-J model reproduces main features of cuprate normal-state properties.

Several dynamical quantities show universal behavior consistent with marginal Fermi-liquid theory.

Quantitative agreement with experimental data is achieved for multiple physical quantities.

Abstract

We review recent results for the properties of doped antiferromagnets, obtained by the numerical analysis of the planar t-J model using the novel finite-temperature Lanczos method for small correlated systems. First we shortly summarize our present understanding of anomalous normal-state properties of cuprates, and present the electronic phase diagram, phenomenological scenarios and models proposed in this connection. The numerical method is then described in more detail. Following sections are devoted to various static and dynamical properties of the t-J model. Among thermodynamic properties the chemical potential, entropy and the specific heat are evaluated. Discussing electrical properties the emphasis is on the optical conductivity and the d.c. resistivity. Magnetic properties involve the static and dynamical spin structure factor, as measured via the susceptibility measurements, the NMR relaxation and the neutron scattering, as well as the orbital current contribution. Follows the analysis of electron spectral functions, being studied in photoemission experiments. Finally we discuss density fluctuations, the electronic Raman scattering and the thermoelectric power. Whenever feasible a comparison with experimental data is performed. A general conclusion is that the t-J model captures well the main features of anomalous normal-state properties of cuprates, for a number of quantities the agreement is even a quantitative one. It is shown that several dynamical quantities exhibit at intermediate doping a novel universal behaviour consistent with a marginal Fermi-liquid concept, which seems to emerge from a large degeneracy of states and a frustration induced by doping the antiferromagnet.