Static and dynamical susceptibility of LaO1-xFxFeAs

Monni M;BERNARDINI, FABIO;Profeta G;Sanna A;Sharma S;Dewhurst J. K;Bersier C;Continenza A;Gross E. K. U;Massidda S.

2010-01-01

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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 chi(0). Using LaO(1-x)F(x)FeAs as a prototype material, in this report we present a detailed ab initio study of chi(0)(q, omega) as a function of doping and of the internal atomic positions. The resulting static chi(0)(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.