Phase diagrams of systems with two coupled order parameters

TL;DR

This paper uses an exactly solvable model to analyze phase diagrams in systems with two coupled order parameters, revealing how fluctuation interactions can induce first-order transitions and anomalous phases.

Contribution

It introduces an exactly solvable model that captures the effects of fluctuation interactions on phase transitions with coupled order parameters.

Findings

Fluctuation interactions can split continuous transitions into two first-order transitions.

Transitions may lead to anomalous phases not predicted by mean field theory.

The effect disappears when fluctuation interactions are suppressed.

Abstract

Within the framework of an exactly solvable model, which takes into account the interaction of fluctuating modes with equal and opposite momenta, we consider phase diagrams in systems with coupled scalar order parameters. We show that, in agreement with the renormalization group theory, the fluctuation interaction can split the continuous disorder-order transition into two phase transitions of the first order. Moreover, the transition may occur into the anomalous, from the mean field theory point of view phase. The effect disappears when the fluctuation interaction is suppressed.