Effect of spinfluctuation due to c- and f-electrons on the superconducting gap of cuprates

Abstract

We propose here a spin fluctuation mediated superconductivity for high temperature copper oxide superconductors. The Hamiltonian consists of superconductivity and spin–spin interaction due to 3d electrons of copper ions and spin fluctuation due to f -electrons which are coupled to the copper spins via Kondo exchange. The spin interactions are considered within the mean-field approximation so that the mean-field Hamiltonian can be diagonalised. The superconducting gap and the anti-ferromagnetic gaps due to c- and f -electrons are calculated by Green’s function technique and are computed self-consistently. These temperature dependent gap parameters are varied by changing superconducting coupling, c-electron magnetic coupling, f -electron magnetic coupling and Kondo coupling. It is observed that there is a strong interplay between superconductivity and two different spin interactions. The results are discussed based on the experimental data.