Magnetic and phonon mechanisms of superconductivity in La${}_{2-x}$Sr${}_x$CuO${}_4$ support each other

Abstract

Strong electron correlations are responsible both for the insulator ground state of undoped La${}_2$CuO${}_4$ and strong antiferromagnetic coupling $J$ between neighbouring spins. We consider magnetic mechanism of superconducting pairing in the effective low energy $t-t^{\prime }-t"-J^{\ast }$ model with all parameters calculated {\it ab initio}. Interaction of strongly correlated electrons with different phonon modes is also incorporated. In a BCS type theory the $d_{x^2-y^2}$ gap is given by a sum of magnetic and phonon contributions. The phonon coupling parameter $\lambda =f(x)G$, where $G$ is a combination 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 a competition of the breathing and buckling modes. Fitting the parameter $G$ from the isotope effect we obtain that magnetic and phonon contributions to the critical temperature $T_c$ work together and are of the same order of magnitude.

10 pages, 5 figures

References in corpus (3)

• A new hybrid LDA and Generalized Tight-Binding method for the electronic structure calculations of strongly correlated electron systems
• Phonons and d-wave pairing in the two-dimensional Hubbard model
• Doping-dependent evolution of low-energy excitations and quantum phase transitions within effective model for High-Tc copper oxides

Cited by in corpus (1)

• Polaronic approach to strongly correlated electron system with strong electron-phonon interaction