On a theoretical model for d-wave to mixed s- and d-wave transition in cuprate superconductors

TL;DR

This paper analyzes a U(3) theoretical model for cuprate superconductors, focusing on the transition from d-wave to mixed s- and d-wave pairing, exploring phase diagrams and thermodynamic properties.

Contribution

It investigates the validity of the Bogoliubov approximation and characterizes phase diagrams and symmetries in a U(3) model for cuprate superconductivity.

Findings

Validated the Bogoliubov approximation for the model

Mapped phase diagrams of s- and d-wave condensates

Analyzed temperature dependence of heat capacity

Abstract

A U(3) model proposed by Iachello for superconductivity in cuprate materials is analyzed. The model consists of s and d pairs (approximated as bosons) in a two-dimensional Fermi system with a surface. The transition occurs between a phase in which the system is a condensate of one of the bosons, and a phase which is a mixture of two types of bosons. In the current work we have investigated the validity of the Bogoliubov approximation, and we used a reduced Hamiltonian to determine a phase diagram, the symmetry of the phases and the temperature dependence of the heat capacity.