The reason why doping causes superconductivity in LaFeAsO

TL;DR

This paper explains how doping induces superconductivity in LaFeAsO by reducing crystal symmetry, which alters electron correlations in a specific band, leading to a stable superconducting state.

Contribution

It provides a group-theoretical analysis showing the link between symmetry reduction due to doping and the emergence of superconductivity in LaFeAsO.

Findings

Doping reduces crystal symmetry in LaFeAsO.

Symmetry reduction modifies electron correlations.

Altered electron behavior leads to superconductivity.

Abstract

The experimental observation of superconductivity in LaFeAsO appearing on doping is analyzed with the group-theoretical approach that evidently led in a foregoing paper (J. Supercond 24:2103, 2011) to an understanding of the cause of both the antiferromagnetic state and the accompanying structural distortion in this material. Doping, like the structural distortions, means also a reduction of the symmetry of the pure perfect crystal. In the present paper we show that this reduction modifies the correlated motion of the electrons in a special narrow half-filled band of LaFeAsO in such a way that these electrons produce a stable superconducting state.