Magnetic and phonon mechanisms of superconductivity in La$ {2-x}$Sr$ x$CuO$ 4$ support each other - Condensed Matter > SuperconductivityReportar como inadecuado




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Abstract: Strong electron correlations are responsible both for the insulator groundstate of undoped La$ 2$CuO$ 4$ and strong antiferromagnetic coupling $J$between neighbouring spins. We consider magnetic mechanism of superconductingpairing in the effective low energy $t - t- t- J^*$ model with allparameters calculated {\it ab initio}. Interaction of strongly correlatedelectrons with different phonon modes is also incorporated. In a BCS typetheory the $d {x^2 - y^2}$ gap is given by a sum of magnetic and phononcontributions. The phonon coupling parameter $\lambda = fxG$, where $G$ is acombination of bare electron-phonon couplings for all modes and the function$f$ depends on the hole concentration $x$ due to strong electron correlations.The main contribution to the only fitting parameter $G$ is determined by acompetition of the breathing and buckling modes. Fitting the parameter $G$ fromthe isotope effect we obtain that magnetic and phonon contributions to thecritical temperature $T c $ work together and are of the same order ofmagnitude.



Autor: S.G. Ovchinnikov, E.I. Shneyder

Fuente: https://arxiv.org/







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