Static and Dynamical Susceptibility of LaO1-xFxFeAs

TL;DR

This paper presents an ab-initio study of the magnetic susceptibility in LaO1-xFxFeAs, revealing insights into its magnetic phases and the role of spin fluctuations in superconductivity.

Contribution

It provides a detailed calculation of the independent-electron susceptibility chi0(q,omega) as a function of doping and atomic positions, linking theoretical predictions with experimental magnetic structures.

Findings

Static susceptibility matches observed magnetic stripe phase.

Doping induces incommensurate magnetic structures.

Results support spin fluctuations' role in pairing mechanism.

Abstract

The mechanism of superconductivity and magnetism and their possible interplay have recently been under debate in pnictides. A likely pairing mechanism includes an important role of spin fluctuations and can be expressed in terms of the magnetic susceptibility chi. The latter is therefore a key quantity in the determination of both the magnetic properties of the system in the normal state, and of the contribution of spin fluctuations to the pairing potential. A basic ingredient to obtain chi is the independent-electron susceptibility chi0. Using LaO1-xFxFeAs as a prototype material, in this report we present a detailed ab-initio study of chi0(q,omega), as a function of doping and of the internal atomic positions. The resulting static chi0(q,0) is consistent with both the observed M-point related magnetic stripe phase in the parent compound, and with the existence of incommensurate magnetic structures predicted by ab-initio calculations upon doping.