Phase Diagram of a Superconducting and Antiferromagnetic System with SO(5) Symmetry

TL;DR

This paper uses Monte Carlo simulations to explore the phase diagram of an SO(5) model for high-temperature cuprates, revealing critical points and symmetry conditions relevant to superconductivity and antiferromagnetism.

Contribution

It provides the first detailed Monte Carlo analysis of the phase diagram for an SO(5) symmetric model in high-Tc cuprates, identifying critical points and phase transition behaviors.

Findings

Identification of a bicritical point where AF and superconductivity lines merge.

Discovery of a tricritical point on the AF transition line.

Observation of first-order AF transition in an external magnetic field.

Abstract

Temperature vs. chemical-potential phase diagrams of an SO(5) model for high-(T_c) cuprates are calculated by Monte Carlo simulation. There is a bicritical point where the second-order antiferromagnetism (AF) and superconductivity transition lines merge tangentially into a first-order line, and the SO(5) symmetry is achieved. In an external magnetic field, the AF ordering is first order in the region where the first-order melting line of flux lattice joins in. There is a tricritical point on the AF transition line from which the AF ordering becomes second order.