Is LaO$ {1-x}$F$ x$FeAs an electron-phonon superconductor - Condensed Matter > SuperconductivityReport as inadecuate

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Abstract: In this paper we calculate the electron-phonon coupling of thenewly-discovered superconductor LaO$ {1-x}$F$ x$FeAs from first-principles,using Density Functional Perturbation Theory. For pure LaOFeAs, the calculatedelectron-phonon coupling constant $\lambda=0.21$ and logarithmic-averagedfrequency $\omega {ln}=206 K$, give a maximum $T c$ of 0.8 K, using thestandard Migdal-Eliashberg theory.For the $F-$doped compounds, we predict even smaller coupling constants, dueto the strong suppression of the electronic Density of States at the Fermilevel. To reproduce the experimental $T c=26 K$, a 5-6 times larger couplingconstant would be needed.Our results indicate that electron-phonon coupling is not sufficient toexplain superconductivity in the newly-discovered LaO$ {1-x}$F$ x$FeAssuperconductor, probably due to the importance of strong correlation effects.

Author: L. Boeri, O. V. Dolgov, A. A. Golubov



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