A model for the doped copper oxide compounds

TL;DR

This paper introduces a relativistic spin-fermion model for cuprates that dynamically treats charge and spin, explaining various phases and high-T_c superconductivity via Bose-Einstein condensation of charge pairs without needing a Fermi sea.

Contribution

It proposes a novel relativistic spin-fermion model that captures the phases of doped cuprates and offers a new understanding of high-T_c superconductivity.

Findings

Model accounts for phases at various doping levels

Qualitative explanation of high-T_c superconductivity

Superconductivity via Bose-Einstein condensation of charge pairs

Abstract

We present a relativistic spin-fermion model for the cuprates, in which both the charge and spin degrees of freedom are treated dynamically. The spin-charge coupling parameter is associated with the doping fraction. The model is able to account for the various phases of the cuprates and their properties, not only at low and intermediate doping but also for (highly) over-doped compounds. In particular, we acquire a qualitative understanding of high-T_c superconductivity through Bose-Einstein condensation of bound charge pairs. The mechanism that binds these pairs does not require a Fermi sea.