Temperature × doping phase diagram of cuprate superconductors

¹ Departamento de Ciências Naturais, Universidade Federal de São João del Rei 36301-000 São João del Rei, MG, Brazil
² Instituto de Física, Universidade Federal do Rio de Janeiro - Caixa Postal 68528, 21941-972 Rio de Janeiro, RJ, Brazil

Received: 14 December 2014
Accepted: 16 April 2015

Abstract

Starting from a spin-fermion model for the cuprate superconductors, we obtain an effective interaction for the charge carriers by integrating out the spin degrees of freedom. Our model predicts a quantum critical point for the superconducting interaction coupling, which sets up a threshold for the onset of superconductivity in the system. We show that the physical value of this coupling is below this threshold, thus explaining why there is no superconducting phase for the undoped system. Then, by including doping, we find a dome-shaped dependence of the critical temperature as charge carriers are added to the system, in agreement with the experimental phase diagram. The superconducting critical temperature is calculated without adjusting any free parameter and yields, at optimal doping , which is comparable to the experimental data.