Magnetic mechanisms of pairing in strongly correlated electron system of copper oxides

TL;DR

This paper develops a multielectron approach to study the electronic structure and magnetic pairing mechanisms in cuprates, revealing Lifshitz transitions, and comparing magnetic and phonon contributions to superconductivity.

Contribution

It introduces a self-consistent LDA+GTB method for cuprates, identifies Lifshitz transitions, and analyzes magnetic and phonon pairing mechanisms in layered cuprates.

Findings

Two Lifshitz-type quantum phase transitions at specific dopings.

Magnetic and phonon pairing contributions are of similar magnitude.

Pressure affects interatomic exchange parameters significantly.

Abstract

The multielectron LDA+GTB approach has been developed to calculate electronic structure of strongly correlated cuprates. At low energies the effective Hamiltonian of the $t - t' - t" - {t_ \bot } - {J^ * } - {J_ \bot }$-model has been derived with parameters coming from the ab initio calculation for LSCO. The electronic structure of LSCO has been calculated self-consistently with the short-range antiferromagnetic order for various doping level. Two Lifshitz-type quantum phase transitions with Fermi surface topology changes have been found at dopings $x_{c1}=0.15$ and $x_{c2}=0.24$. Its effect on normal and superconducting properties has been calculated. The interatomic exchange parameter and its pressure dependence has been calculated within LDA+GTB scheme. The magnetic mechanisms of d-wave pairing induced by static and dynamical spin correlations are discussed. Simultaneous treatment of magnetic and phonon pairing results in the conclusion that both contributions are of the same order. For two layer cuprates like YBCO the interlayer hopping and exchange effects on the electronic structure and doping dependence of $T_c$ is discussed as well as the Coulomb interaction induced mechanism of pairing.