A unified theory for the cuprates, iron-based and similar superconducting systems: non-Fermi-liquid to Fermi-liquid crossover, low-energy and waterfall anomalies

TL;DR

This paper presents a unified theoretical framework for cuprates and Fe-based superconductors, explaining their complex phase diagrams, spectral anomalies, and the crossover from non-Fermi-liquid to Fermi-liquid behavior using auxiliary particles and a Lagrange Bose field.

Contribution

It introduces a novel unified theory that captures the low-energy excitations and anomalies across different high-temperature superconductors, unifying their phase behavior and spectral features.

Findings

Accurately describes the phase diagram and non-Fermi-liquid to Fermi-liquid crossover.

Explains spectral anomalies like kink- and waterfall-like features.

Accounts for the temperature and frequency dependence of carrier density and scattering rates.

Abstract

A unified theory is outlined for the cuprates, Fe-based, and related superconductors. Their low-energy excitations are approached in terms of auxiliary particles representing combinations of atomic-like electron configurations, and the introduction of a Lagrange Bose field enables their treatment as bosons or fermions. This theory correctly describes the observed phase diagram of the cuprates, including the non-Fermi-liquid to FL crossover in the normal state, the existence of Fermi arcs below T^* and of "marginal-FL" behavior above it. The anomalous behavior of numerous physical quantities is accounted for, including kink- and waterfall-like spectral features, the drop in the scattering rates below T^* and more radically below T_c, and an effective increase in the density of carriers with T and \omega, reflected in transport, optical and other properties. Also is explained the correspondence between T_c, the resonance-mode energy, and the increase in the gap below T_c.