The possibility of two-exciton pairing in singlet and in triplet states

TL;DR

This paper introduces a 2D exciton model suggesting two-exciton pairing in cuprates, potentially explaining superconductivity and normal state anomalies, with a phase diagram showing insulator-superconductor-metal transitions.

Contribution

It presents a novel exciton-based model for cuprates that accounts for both singlet and triplet pairings and their roles in different electronic phases.

Findings

Two-exciton pairing possible in cuprates.

Ground state resembles Bose condensation with a generalized Gutzwiller projection.

Phase diagram includes insulator, superconductor, and metal phases with doping.

Abstract

We propose a two-dimensional exciton model showing the possibility of two-exciton pairing in cuprates, both in singlet and in triplet states. The former is assumed to be responsible for the superconductivity and the latter for the unusual normal state properties. The ground state is found to be a projection of the Bose condensation of N/2 mobile bosons with a \eta projection operator which is a generalization of the Gutzwiller projection operator. The phase diagram of the model shows insulator-superconductivity and superconductivity-metal transitions with doping.